Halobenzene liquid crystals

ABSTRACT

Compounds of the formula ##STR1## wherein X 1  denotes fluorine or chlorine and X 2  denotes hydrogen, fluorine or chlorine; R 1  is 3E-alkenyl, 4-alkenyl, 2E-alkenyloxy or 3-alkenyloxy; n stands for the number 0 or 1; one of the groups Y 1  and Y 2  is a single covalent bond, --COO--, --OOC--, --CH 2  CH 2  --, --CH 2  O-- or --OCH 2  -- and the other of the groups Y 1  and Y 2  is a single covalent bond; and rings A 1  and A 2  each individually are substituted or unsubstituted trans-1,4-cyclohexylene, in which optionally 2 non-adjacent CH 2  groups are replaced by oxygen, or substituted or unsubstituted 1,4-phenylene, in which optionally 1 CH group or 2 CH groups is/are replaced by nitrogen; with the proviso that X 2  denotes fluorine or chlorine and/or Y 1  or Y 2  denotes --CH 2  O-- or --OCH 2  -- when simultaneously X 1   is fluorine and R 1  is 3E-alkenyl, 
     and their use for liquid crystalline mixtures and electro-optical purposes.

This is a division of application Ser. No. 07/262,652 filed Oct. 26,1988 now U.S. Pat. No. 5,230,826.

BACKGROUND

1. Field of the Invention

The present invention is concerned with novel halobenzene derivatives,liquid crystalline mixtures which contain these compounds as well astheir use for electro-optical purposes.

2. Description

Liquid crystals are used primarily as dielectrics in indicating devices,since the optical properties of such substances can be influenced by anapplied voltage. Electro-optical devices based on liquid crystals arewell-known to the person skilled in the art and can be based on variouseffects. Examples of such devices are cells having dynamic scattering,DAP cells (deformation of aligned phases), guest/host cells, TN cellshaving a twisted nematic structure, STN cells ("super-twisted nematic"),SBE cells ("super-birefringence effect") and OMI cells ("optical modeinterference"). The most common indicating devices are based on theSchadt-Helfrich effect and have a twisted nematic structure.

The liquid crystal materials must have a good chemical and thermalstability and a good stability towards electric fields andelectromagnetic radiation. Further, the liquid crystal materials shouldhave a low viscosity and should give short response times, low thresholdpotentials and a high contrast in the cells. Furthermore, at usualoperating temperatures from about -300° C. to about +80° C., especiallyfrom about -200° C. to about +600° C., they should have a suitablemesophase for example a nematic or cholesteric mesophase for theabove-mentioned cells. Further properties such as the electricalconductivity, the dielectric anisotropy and the optical anisotropy mustfulfill different requirements depending on the type of cell and fieldof application. For example, materials for cells having a twistednematic structure should have a positive dielectric anisotropy and anelectrical conductivity which is as low as possible. In addition to thegeneral interest in compounds having a high optical anisotropy, therehas recently been an increased interest in materials having a lowoptical anisotropy, especially for actively addressed liquid crystalindicators, for example, for TFT applications ("thin film transistor")in television sets, whereby, however, effects such as the occurrence ofhighly ordered smetic phases or an increase in the threshold potentialand in the response times, which are frequently observed in suchmaterials, should be avoided as far as possible.

Since liquid crystals are generally used as mixtures of severalcomponents, it is important that the components have a good miscabilitywith one another.

SUMMARY OF THE INVENTION

The present invention provides halobenzene derivatives of the formula##STR2## wherein X¹ denotes fluorine or chlorine and X² denoteshydrogen, fluorine or chlorine; R¹ is 3E-alkenyl, 4-alkenyl,2E-alkenyloxy or 3-alkenyloxy; n stands for the number 0 or 1; one ofthe groups Y¹ and Y² is a single covalent bond, --COO--, --OOC--, --CH₂CH₂ --, --CH₂ O-- or --OCH₂ -- and the other of the groups Y¹ and Y² isa single covalent bond; and rings A¹ and A² each individually aresubstituted or unsubstituted trans-1,4-cyclohexylene, in whichoptionally 2 non-adjacent CH₂ groups are replaced by oxygen, orsubstituted or unsubstituted 1,4-phenylene, in which optionally 1 CHgroup or 2 CH groups is/are replaced by nitrogen; with the proviso thatX² denotes fluorine or chlorine and/or Y¹ or Y² denotes --CH₂ O-- or--OCH₂ -- when simultaneously X¹ is fluorine and R¹ is 3E-alkenyl.

The compounds in accordance with the invention generally have a positivedielectric anisotropy. Although in comparison to cyano compounds theyare relatively less polar, they give amazingly low threshold potentialswhich are often lower than those of cyano compounds. Further, they havea high stability and a lower electrical conductivity than the cyanocompounds.

Surprisingly, the compounds in accordance with the invention give, inaddition to the low threshold potentials, simultaneously short responsetimes. Highly ordered smectic phases are completely or at least largelysuppressed, and the melting points are often lowered.

The compounds in accordance with the invention are therefore especiallysuitable as components of nematic and cholesteric mixtures. The bicycliccompounds of formula I are primarily suitable as doping agents forproducing especially low threshold potentials, response times andmelting points. The tricyclic compounds of formula I generally have abroad nematic or cholesteric mesophase range and are suitable forproducing broad mesophase ranges in mixtures, whereby simultaneously thethreshold potentials and response times remain amazingly low.

By virtue of the good solubility of the compounds of formula I with oneanother and in known liquid crystals comparatively high concentrationscan generally be used and at the same time the number of components inliquid crystalline mixtures can be reduced. This is especially true alsofor the tricyclic compounds of formula I.

The optical anisotropy of the compounds of formula I can vary in a widerange depending on the choice of rings A¹ and B¹, with saturated ringsleading to low values of the optical anisotropy and aromatic ringsleading to high values of the optical anisotropy. The advantagesmentioned above apply in the entire range and are found especially alsoin the compounds having a low optical anisotropy.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed toward halobenzene derivatives of theformula ##STR3## wherein X¹ is fluorine or chlorine and X² is hydrogen,fluorine or chlorine; R¹ is 3E-alkenyl, 4-alkenyl, 2E-alkenyloxy or3-alkenyloxy; n is the integer 0 or 1; one of the groups Y¹ and Y² is asingle covalent bond, --COO--, --OOC--, --CH₂ CH₂ --, --CH₂ O-- or--OCH₂ -- and the other of the groups Y¹ and Y² is a single covalentbond; and each of rings A¹ and A² individually istrans-1,4-cyclohexylene, trans-1,4-cyclohexylene in which 2 non-adjacentCH₂ groups are replaced by oxygen, 1,4-phenylene, or 1,4-phenylene inwhich 1 CH group or 2 CH groups is/are replaced by nitrogen, the abovesubstituents for rings A¹ and A² being unsubstituted or substituted withat least one of cyano, lower alkyl or halo; with the proviso that X² isfluorine or chlorine and/or Y¹ or Y² is --CH₂ O-- or --OCH₂ -- whensimultaneously X¹ is fluorine and R¹ is 3E-alkenyl.

The terms "3E-alkenyl", "4-alkenyl", "2E-alkenyloxyl" and"3-alkenyloxyl" in formula I embrace straight-chain and branchedresidues. There are generally preferred the straight-chain residues suchas 3-butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 3E-octenyl,3E-nonenyl, 3E-decenyl, 4-pentenyl, 4-hexenyl, 4-heptenyl, 4-octenyl,4-nonenyl, 4-decenyl, allyloxy, 2E-butenyloxy, 2E-pentenyloxy,2E-hexenyloxy, 2E-heptenyloxy, 2E-octenyloxy, 2E-nonenyloxy,3-butenyloxy, 3-pentenyloxy. 3-hexenyloxy, 3-heptenyloxy, 3-octenyloxy,3-nonenyloxy and the like. Compounds having a branched optically activeresidue R¹ such as for example. 5-methyl-3E-heptenyl and6-methyl-4-octenyl are primarily of interest as chiral doping agentsand/or cholesteric liquid crystals. In the case of 4-alkenyl and3-alkenyloxy residues R¹, which can be present in the E- or Z-form, theZ-form is generally preferred. Conveniently, the 3E-alkenyl residueshave about 4-15 carbon atoms, the 4-alkenyl residues have about 5-15carbon atoms, the 2E-alkenyloxy residues have about 3-14 carbon atomsand the 3-alkenyloxy residues have about 4-14 carbon atoms. Alkenylresidues with up to 10 carbon atoms and alkenyloxy residues with up to 9carbon atoms are generally preferred. Especially preferred residues R¹are 3-butenyl, 3E-pentenyl, 4-pentenyl, allyloxy and 3-butenyloxy.

The term "substituted or unsubstituted trans-1,4-cyclohexylene in whichoptionally 2 non-adjacent CH₂ groups are replaced by oxygen" (alsodenoted in the scope of the present invention as "saturated ring")embraces especially trans-1,4-cyclohexylene and trans-m-dioxane-2,5-diylas well as rings which are substituted with conventional substituentsusual in liquid crystals such as cyano, lower alkyl (e.g. methyl), orhalo (e.g. fluorine or chlorine), for example1-cyano-trans-1,4-cyclohexylene or 2-methyl-trans-1,4-cyclohexylene.

The term "substituted or unsubstituted 1,4-phenylene in which optionally1 CH group or 2 CH groups is/are replaced by nitrogen" (also denoted inthe scope of the present invention as "aromatic ring") embracesespecially 1,4-phenylene, pyridine-2,5-diyl, pyrazine-2,5-diyl andpyrimidine-2,5-diyl as well as rings which are substituted withconventional substituents which are usual in liquid crystals such ascyano, lower alkyl (e.g. methyl), or halo (e.g. fluorine or chlorine),for example 2-cyano-1,4-phenylene, 2-fluoro-1,4-phenylene,2-chloro-1,4-phenylene or 2-methyl-1,4-phenylene.

The term "halo" denotes fluoro, chloro, bromo and iodo. The term "loweralkyl" denotes straight or branched chain saturated hydrocarbon groupsof 1 to 4 carbon atoms.

In general, compounds of formula I with unsubstituted rings A¹ and A²are preferred. However, if desired, the dielectric anisotropy, themesophase range, the solubility and the like can be modified by usingsubstituted rings.

Formula I embraces the compounds of the following formulas ##STR4##wherein R¹, X¹, X² and rings A¹ and A² in each case have the abovesignificances.

In the above formulas I, I-7 and I-8 to I-17 ring A² preferably standsfor substituted or unsubstituted trans-1,4-cyclohexylene, forsubstituted or unsubstituted 1,4-phenylene or, when ring A¹ issubstituted or unsubstituted trans-1,4-cyclohexylene or substituted orunsubstituted 1,4-phenylene, also for pyrimidine-2,5-diyl ortrans-m-dioxane-2,5-diyl. Those compounds in which ring A² stands fortrans-1,4-cyclohexylene are generally especially preferred. Atrans-m-dioxane-2,5-diyl group which is optionally present as ring A² ispreferably linked with R¹ in the 5-position; in this case ring A¹preferably denotes trans-1,4-cyclohexylene.

Further, in the above formulas I and I-1 to I-17 ring A¹ in each casepreferably stands far substituted or unsubstitutedtrans-1,4-cyclohexylene, for substituted or unsubstituted 1,4-phenyleneor for pyridine-2,5-diyl, its pyrimidine-2,5-diyl or pyrazine-2,5-diyl.Of the compounds of formulas I, I-7 and I-8 to I-17 there are generallyespecially preferred those in which ring A¹ has one of the mentionedpreferred significances and denotes especially an unsubstituted groupand ring A² simultaneously is trans-1,4-cyclohexylene.

Examples of preferred groups of compounds of formula I are the compoundsof the formulas ##STR5## wherein R¹, X¹, X², Y¹ and Y² have the abovesignificances.

Of the compounds of the above formulas I, I-1 to I-32, I-33 and 1-34there are generally preferred those in which in each case X¹ is fluorineand X² is hydrogen or X¹ and X² are fluorine or X¹ is chlorine and X² ishydrogen. Further, of the compounds of formulas I-18, I-23 to I-31, I-33and I-34 there are generally preferred those in which in each case Y¹ isa single covalent bond or --COO--. Preferred residues R¹ in the aboveformulas I and I-1 to I-34 are 3-butenyl, 3E-pentenyl and 4-pentenyl.

The compounds of formula I can be prepared in a manner known per se. forexample according to the methods described in EP-A-122389, EP-A-167912and EP-A-168683, and in U.S. Pat. Nos. 4,676,604, 4,621,901 and U.S.patent application Ser. No. 53778/87.

The compounds of formula I in which R¹ is 2E-alkenyloxy or 3-alkenyloxyare generally obtained most easily by etherifying the correspondinghydroxy compound with a 2E-alkenyl halide or a 3-alkenyl halide,preferably a 2E-alkenyl bromide or a 2E-alkenyl iodide, respectively, a3-alkenyl bromide or 3-alkenyl iodide. The required hydroxy compoundsare known or are analogues of known compounds.

The compounds of formula I in which R¹ is 3E-alkenyl or 4-alkenyl aregenerally obtained by reacting the corresponding propionaldehyde orbutyraldehyde in the presence of a strong base with analkyl-triarylphosphonium halide, preferably with analkyl-triphenylphosphonium chloride or with analkyl-triphenylphosphonium bromide. The reaction can be effected underthe conditions which are usual for wittig reactions. The requiredpropionaldehydes and butyraldehydes can be obtained from thecorresponding compounds having a formyl-substituted ring (derivatives ofcyclohexanecarboxaldehyde, benzaldehyde etc) or the corresponding cyclicketones (cyclohexanone derivatives) by successive chain lengthening viathe acetaldehydes. The chain lengthening can be effected for example, ineach case by a Wittig reaction with a methoxymethyl-triarylphosphoniumhalide, preferably methoxymethyl-triphenylphosphonium chloride, andsubsequent hydrolysis (for example with acetic acid). Further, a chainlengthening by 3 carbon atoms can also be effected for example, by aWittig reaction with a 2-(1,3-dioxolan-2-yl)ethyl-triarylphosphoniumhalide, preferably 2-(1,3-dioxolan-2-yl)ethyl-triphenylphoshoniumbromide, subsequent catalytic hydrogenation of the C--C double bond andhydrolysis of the dioxolane ring, for example, with acetic acid. Thelatter method has, moreover, the advantage that, prior to the hydrolysisof the dioxolane ring, other functional groups can, if desired, beintroduced readily into the molecule or converted.

When the central portion of formula I has a group which can be formedreadily by a final linkage such as, for example, an ester group ormethyleneoxy group for Y¹ or Y² or a dioxane ring for ring A¹ and A², itcan be advantageous to prepare the corresponding educt (for example,carboxylic acid, hydroxy compound, halo compound, 1,3-diol, aldehyde)containing the alkenyl group or the alkenyloxy group in an analogousmanner to the methods described above. Subsequently, for example, thecarboxylic acid obtained can be esterified with a suitable hydroxycompound (to give a compound of formula I in which Y¹ or Y² is --COO--),or the hydroxy compound obtained can be esterified with a suitablecarboxylic acid or a suitable carboxylic acid chloride (to give acompound of formula I in which Y¹ or Y² is --OOC--), or a hydroxycompound obtained can be etherified with a suitable halo compound(especially a bromo or iodo compound) (to give a compound of formula Iin which Y¹ or Y² is -- OCH₂ --) or a halo compound obtained (especiallya bromo or iodo compound) can be etherified with a suitable hydroxycompound (to give a compound of formula I in which Y¹ or Y² is --CH₂O--) or a 1,3-diol obtained can be reacted with a suitable aldehyde oran aldehyde obtained can be reacted with a suitable 1,3-diol (to give acompound of formula I in which ring A¹ or A² istrans-m-dioxane-2,5-diyl).

The indicated reactions can be effected in each case in a manner knownper se. The required starting materials are known or can be prepared ina manner known per se. The above synthesis variants and the reactionconditions are illustrated further in the Synthesis Examples.

The compounds of formula I can be used in the form of mixtures with oneanother and/or with other liquid crystal components such as for example,with substances from the classes of Schiff's bases, azobenzenes,azoxybenzenes, phenylbenzoates, cyclohexanecarboxylic acid phenylesters, cyclohexanecarboxylic acid cyclohexyl esters, biphenyls,phenylcyclohexanes, cyclohexylcyclohexanes, phenylpyrimidines,cyclohexylpyrimidines, phenyldioxanes, 2-cyclohexyl-1-phenylethanes,terphenyls, cyclohexylbiphenyls, cyclohexylphenylpyrimidines and thelike. Such substances are known to the person skilled in the art andmany of them are, moreover, commercially available.

The liquid crystalline mixtures in accordance with the invention containat least two components, of which at least one component is a compoundof formula I. A second component and optionally further components canbe further compounds of formula I or other liquid crystal components.The compounds of formula I are especially suitable for nematic mixturesor, insofar as at least one component of the mixture is opticallyactive, also for cholesteric mixtures.

The compounds of formula I in which n stands for the number 0 and R¹ is4-alkenyl are generally advantageously used together with other nematicor cholesteric materials, for example together with tricyclic compoundsof formula I. The mixtures in accordance with the invention thereforepreferably contain one or more compounds of formula I and a nematic orcholesteric carrier material.

Having regard to the good solubility of the compounds of formula I andhaving regard to their good miscibility with one another, their amountin the mixtures in accordance with the invention can be relatively high.However, an amount of 1-50 wt.%, especially about 5-30 wt.%, ofcompounds of formula I is generally preferred.

The mixtures in accordance with the invention preferably contain inaddition to one or more compounds of formula I one or more compoundsfrom the group of compounds of the formula ##STR6## wherein R² and R⁷each are alkyl, 1E-alkenyl, 3E-alkenyl or 4-alkenyl; R³ is cyano, --NCS,alkyl, 1E-alkenyl, 3E-alkenyl, 4-alkenyl, alkoxy, 2E-alkenyloxy or3-alkenyloxy; R⁴ is alkyl, 3E-alkenyl or 4-alkenyl; R⁵ is cyano, --NCS,alkyl, 3E-alkenyl, 4-alkenyl, alkoxy, 2E-alkenyloxy or 3-alkenyloxy; R⁶is cyano, alkyl, 3E-alkenyl, 4-alkenyl, alkoxy, 2E-alkenyloxy or3-alkenyloxy; Z is a single covalent bond or --CH₂ --CH₂ --; R⁸ iscyano, alkoxy, 2E-alkenyloxy, 3-alkenyloxy, alkyl, 1E-alkenyl,3E-alkenyl or 4-alkenyl; R⁹ denotes alkyl, 1E-alkenyl or, when one ofthe groups Y¹ and Y² is a single covalent bond, --COO--, --OOC-- or--CH₂ CH₂ -- and the other of the groups Y¹ and Y² is a single covalentbond, also 3E-alkenyl; and n, Y¹, Y² and rings A¹ and A² have the abovesignificances.

The alkyl, alkenyl, alkoxy and alkenyloxy residues R² -R⁹ in formulasII-XIV are preferably straight-chain residues. They preferably have upto 12, particularly up to 7, carbon atoms.

The compounds of formula XI in which R² is 1E-alkenyl, 3E-alkenyl or4-alkenyl are novel. They can be prepared according to the methodsillustrated in the Synthesis Examples.

The mixtures in accordance with the invention can also contain opticallyactive compounds (for example, optically active 4'-alkyl- or4'-alkoxy-4-biphenylcarbonitriles) and/or dichroic coloring substances(for example, azo, azoxy or anthraquinone coloring substances). Theamount of such compounds is determined by the solubility, the desiredpitch, colour, extinction and the like. The amount of optically activecompounds and dichroic coloring substances generally amounts to in eachcase a maximum of about 10 wt.% in the total mixture.

The preparation of the mixtures in accordance with the invention and thepreparation of the electro-optical devices can be effected in a mannerknown per se.

The preparation of the compounds of formula I and the novel compounds offormula XI as well as liquid crystal-line mixtures containing thesecompounds are illustrated further by the following Examples. C is acrystalline phase, S_(B) is a smectic B phase, N is a nematic phase andI is the isotropic phase. V₁₀ and V₅₀ denote respectively the voltagefor 10% and 50% transmission, p=(V ₅₀ -V₁₀)/V₁₀ is a measurement of thesteepness of the transmission curve, t_(on) and t_(off) denoterespectively the switching-on time and the switching-off time and Δndenotes the optical anisotropy. Unless otherwise stated, percentages andratios relating to solvent mixtures are expressed in volume, purity datadetermined by gas chromatography are expressed in area % and theremaining percentages and ratios are expressed in weight, temperaturesare in degrees Celsius (°C.), normal pressure is about 1 atmosphere androom temperature is about 23° C. The petroleum ether is a well-knownmixture of low-boiling hydrocarbons. Unless indicated otherwise, theexamples were carried out as written.

EXAMPLE 1

a) A solution of 1.71 g oftrans-4-[trans-4-(4-pentenyl)-cyclohexyl]cyclohexanecarbonitrile(prepared according to Example 2) in 30 ml of diethylene glycol wastreated with 3.11 g of potassium hydroxide and stirred at 130° C. for 3hours. The mixture was then poured on to ice-water, acidified with 25percent hydrochloric acid and extracted three times with diethyl ether.The organic phases were combined, washed three times with water, driedover magnesium sulfate and evaporated. Recrystallization of the brown,crystalline residue (1.74 g) from 30 ml of hexane gave 996 mg oftrans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexanecarboxylic acid asyellowish crystals.

b) A solution of 996 mg oftrans-4-[trans-4-(4-pentenyl)-cyclohexyl]cyclohexanecarboxylic acid in80 ml of methylene chloride was treated with 752 mg of p-fluorophenol,61 mg of 4-(dimethylamino)pyridine and 1.03 g ofdicyclohexylcarbodiimide and stirred at room temperature for 15 hours.The reaction mixture was subsequently filtered. The filtrate wasevaporated and the residue obtained was purified by chromatography onsilica gel with ethyl acetate/petroleum ether (vol. 3:97).Crystallization of the product obtained (1.24 g) from 40 ml of hexanegave 757 mg of puretrans-4-[trans-4-(4-pentenyl)cyclohexyl]-cyclohexanecarboxylic acid4-fluorophenyl ester with m.p. (C-N) 70.3° C. and cl.p. (N-I) 158.7° C.

The following compounds can be prepared in an analogous manner:

trans-4-(4-Pentenyl)cyclohexanecarboxylic acid 4-fluorophenyl ester,m.p. 31.3° C.;

trans-4-(4-pentenyl)cyclohexanecarboxylic acid 3,4-di-fluorophenylester, m.p. 12.4° C.;

trans-4-(4-pentenyl)cyclohexanecarboxylic acid 4-chlorophenyl ester:

4-(4-pentenyl)benzoic acid 4-fluorophenyl ester;

4-(4-pentenyl)benzoic acid 3,4-diflurophenyl ester;

4-(3-butenyloxy)benzoic acid 4-fluorophenyl ester, m.p. 65° C.;

4-(3-butenyloxy)benzoic acid 3,4-difluorophenyl ester, m.p. 47.5° C.;

4-(3-butenyloxy)benzoic acid 4-chlorophenyl ester;

trans-4-[trans-4-(4-pentenyl)cyclohexyl)cyclohexanecarboxylic acid3,4-difluorophenyl ester;

trans-4-[trans-4-(4-pentenyl)cyclohexyllcyclohexanecarboxylic acid4-chlorophenyl ester;

trans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexanecarboxylic acid3-chloro-4-fluorophenyl ester;

trans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexanecarboxylic acid3-fluoro-4-chlorophenyl ester;

4-[trans-4-(4-pentenyl)cyclohexyl]benzoic acid 4-fluorophenyl ester:

4-[trans-4-(4-pentenyl)cyclohexyl)benzoic acid 3,4-di-fluorophenylester;

5-[trans-4-(4-pentenyl)cyclohexyl]-2-pyrimidinecarboxylic acid4-fluorophenyl ester;

2-[trans-4-(4-pentenyl)cyclohexyl]-5-pyrimidinecarboxylic acid4-fluorophenyl ester;

4-[5-(4-pentenyl)-2-pyrimidinyl]benzoic acid 4-fluorophenyl ester;

4-[2-(4-pentenyl)-5-pyrimidinyl]benzoic acid 4-fluorophenyl ester;

trans-4-(4Z-hexenyl)cyclohexanecarboxylic acid 4-fluorophenyl ester;

trans-4-(4Z-hexenyl)cyclohexanecarboxylic acid 3,4-di-fluorophenylester;

4-(3Z-pentenyloxy)benzoic acid 4-fluorophenyl ester;

trans-4-[trans-4-(4Z-hexenyl)cyclohexyl]cyclohexanecarboxylic acid4-fluorophenyl ester;

4-[trans-4-(4Z-hexenyl)cyclohexyl]benzoic acid 4-fluorophenyl ester;

trans-4-(3-butenyl)cyclohexanecarboxylic acid 3,4-di-fluorophenyl ester,m.p. 42° C.;

trans-4-(3-butenyl)cyclohexanecarboxylic acid 4-chlorophenyl ester;

4-allyoxybenzoic acid 4-fluorophenyl ester;

4-allyloxybenzoic acid 3,4-difluorophenyl ester;

4-allyloxybenzoic acid 4-chlorophenyl ester;

trans-4-[trans-4-(2-butenyl)cyclohexyl]cyclohexanecarboxylic acid3,4-difluorophenyl ester,, m.p. (C-N) 55.1° C. cl.p. (N-I) 153.6° C.;

trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarboxylic acid4-chlorophenyl ester, m.p. (C-N) 78.30° C. cl.p. (N-I) 213.5° C.;

trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarboxylic acid3-chloro-4-fluorophenyl ester;

trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarboxylic acid3-fluoro-4-chlorophenyl ester;

4-[trans-4-(3-butenyl)cyclohexyl]benzoic acid 3,4-di-fluorophenyl ester;

trans-4-(3E-pentenyl)cyclohexanecarboxylic acid 3,4-difluorophenylester;

4-(2E-butenyloxy)benzoic acid 4-fluorophenyl ester.

EXAMPLE 2

a) 140.9 g of 2-(1,3-dioxolan-2-yl)ethyl-triphenylphosphonium bromidewere suspended in 4.5 1 of tetrahydrofuran while gassing with nitrogenand the suspension was treated at 0° C. within 5 minutes with 36.8 g ofpotassium tert.butylate. The orange suspension was stir-red at roomtemperature for a further I hour and treated within 5 minutes with 46.1g of 4-(4-oxocyclohexyl)benzamide. The reaction mixture was stirred atroom temperature for a further 4.5 hours and then concentrated in avacuum. The yellowish crystals obtained (212.5 g) were treated with 1.21 of diethyl ether. The mixture was stirred at room temperature for 30minutes and then suction filtered. The residue was washed with diethylether and then suspended in 700 ml of water. The mixture was stirred for15 minutes and then suction filtered. The residue was washed with waterand dissolved while heating in 600 ml of dioxan. The solution was leftto cool to room temperature. The separated crystals were removed byfiltration under suction, washed with a small amount of dioxan andhexane and dried at 60° C. in a vacuum, whereby there were obtained 39.2g of crystalline4-[4-[2-(1,3-dioxolan-2-yl)ethylidene]cyclo-hexyl]benzamide with m.p.209°-212° C. Working-up of the mother liquor (72.6 g) gave a further 7.7g of product and 64.2 g of a second mother liquor.

b) A mixture of 500 mg of4-[4-[2-(1,3-dioxolan-2-yl)-ethylidene]cyclohexyl]benzamide and 20 ml ofdioxan/triethylamine (vol. 9:1) was hydrogenated by means of 500 mg of10 percent platinum-charcoal for 2 hours. The reaction mixture was thenfiltered and the filtrate was evaporated. Recrystallization of theevaporation residue from 40 ml of dioxan gave 230 mg of4-[trans-4-[2-(1,3-dioxolan-2-yl) ethyl]cyclohexyl]benzamide ascolorless crystals.

c) 27 g of 4-[trans-4-[2,-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]benzamidewere hydrogenated for 8 hours with 5 g of 5 percent ruthenium-charcoalin dioxan at 120° C. and 40 bar hydrogen. The crude product (25 g)obtained after filtration and washing with tetrahydrofuran contained 69%of the cis isomer and 25% of the trans isomer of4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]cyclohexanecarboxamide.

d) 42 g of crude4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]-cyclohexyl]cyclohexanecarboxamidewere suspended in 500 ml of ethylene glycol while gassing with argon andthen treated with 19 g of solid potassium hydroxide. The mixture washeated to 180° C. (bath temperature) for 5 hours while stirring. Aftercooling the reaction mixture was poured into 500 ml of water, acidifiedto pH about 3 with 10 percent hydrochloric acid and extracted threetimes with 300 ml of methylene chloride each time. The combined organicphases were washed once with 500 ml of 1 percent hydrochloric acid andtwice with 500 ml of water each time, dried over magnesium sulfate,filtered and evaporated. The dark brown crude product (41 g) waspurified by chromatography on silica gel with ethyl acetate.Crystallization of the product obtained (36 g) from acetone gave 13.8 gof pure trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]cyclohexanecarboxylic acid. Working-up of the motherliquor gave a further 2.5 g of pure product.

e) 18 g oftrans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl]-cyclohexyl)cyclohexanecarboxylicacid were dissolved in 600 ml of chloroform while gassing with argon andthe solution was treated dropwise at 0° C. while stirring within 3minutes with a solution of 7.2 ml of ethyl chloroformate in 40 ml ofchloroform. The reaction solution was stirred for a further 30 minutes.Ammonia gas was then conducted into the solution during 10 minutes. Themixture was stirred at 0° C. for a further 30 minutes and then extractedtwice with 300 ml of water each time. The aqueous phases wereback-extracted with 100 ml of chloroform each time. The combined organicphases were dried over magnesium sulfate, filtered and evaporated.Recrystallization of the brown crystalline crude product obtained (19 g)from 800 ml of methylene chloride gave 13 g oftrans-4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]-cyclohexyl]cyclohexanecarboxamideas pale brown crystals.

f) 2.1 g oftrans-4-[trans-4-[2-(1,3-dioxolan-2-yl)-ethyl]cyclohexyl]cyclohexanecarboxamidewere suspended in 60 ml of dimethylformamide while gassing with argon.The suspension was treated with 1.32 ml of pyridine and 0.898 ml ofmethanesulfochloride and stirred at 60° C. (bath temperature) for 1.5hours. The reaction solution was subsequently partitioned in methylenechloride and 10 percent hydrochloric acid. The aqueous phase wasextracted twice with 100 ml of methylene chloride each time. The organicphases were washed twice with 100 ml of water each time, dried overmagnesium sulfate, filtered and concentrated. There were thus obtained2.5 g of trans-4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]cyclohexanecarbonitrile as yellow crystals in a purityof 96%.

g) 3.0 g of crudetrans-4-[trans-4-[2-(I.3-dioxolan-2-yl)ethyl]cyclohexyl)cyclohexanecarbonitrilewere suspended in 50 ml of water, 25 ml of glacial acetic acid and 10 mlof dioxan while gassing with argon and stirred at 100° C. for 1 hour.Thereafter, the reaction solution was treated with 100 ml of water. Theaqueous phase was separated and extracted three times with 100 ml ofdiethyl ether each time. The organic phases were washed with 100 ml ofdilute sodium hydrogen carbonate solution and with 100 ml of water,dried over magnesium sulfate, filtered and concentrated.Recrystallization of the yellow crystals obtained (2.25 g) from 60 ml ofhexane gave 1.98 g of3-[trans-4-(trans-4-cyanocyclohexyl)cyclohexyl]-propionaldehyde ascolorless crystals.

h) 4.11 g of methoxymethyl-triphenylphosphonium chloride were suspendedin 60 ml of tert.butyl methyl ether while gassing with argon and treatedat room temperature within 2 minutes with 1.26 g of potassiumtert.butylate. The suspension was stirred at room temperature for afurther 1 hour, then cooled to 0° C. and treated dropwise within 5minutes with a solution of 1.98 g of3-[trans-4-(trans-4-cyanocyclohexyl)cyclohexyl]propionaldehyde in 25 mlof tert.butyl methyl ether. The reaction mixture was stirred at 0° C.for a further 45 minutes, then diluted with 100 ml of water andextracted three times with 100 ml of diethyl ether each time. Theorganic phases were washed twice with 100 ml of water each time, driedover magnesium sulfate, filtered and concentrated. Chromatographicpurification of the crude product (5.1 g) on silica gel at 0.5 bar withethyl acetate/petroleum ether (vol. 5:95) gave 2.0 g oftrans-4-[trans-4-(4-methoxy-3-butenyl)cyclohexyl)cyclohexanecarbonitrileas a colorless milky oil.

i) 1.65 g oftrans-4-[trans-4-(4-methoxy-3-butenyl)cyclohexyl]cyclohexanecarbonitrilewere suspended in 50 ml of water, 25 ml of glacial acetic acid and 12 mlof dioxan while gassing with argon. The suspension was stirred at 80° C.(bath temperature) for 2 hours and then diluted with 50 ml of water. Theaqueous phase was separated and extracted three times with 100 ml ofdiethyl ether each time. The organic phases were washed twice with 100ml of water each time, then with 100 ml of saturated sodium hydrogencarbonate solution and again with 100 ml of water, then dried overmagnesium sulfate, filtered and concentrated. There were thus obtained1.5 g of 4-[trans-4-(trans-4-cyanocyclohexyl)cyclohexyl]butyraldehyde ascolorless crystals.

j) 3.28 g of methyltriphenylphosphonium bromide were suspended in 40 mlof tert.butyl methyl ether while gassing with argon. The suspension wastreated at room temperature within 1 minute with 962 mg of potassiumtert.butylate and stirred for I hour. The mixture was subsequentlycooled to 0° C., treated dropwise within 3 minutes with a solution of1.5 g of 4-[trans-4-(trans-4-cyanocyclohexyl)cyclohexyl]butyraldehyde in20 ml of tert.butyl methyl ether and stirred at 0° C. for a further 45minutes. Thereafter, the reaction mixture was diluted with 80 ml ofwater and extracted three times with 100 ml of petroleum ether eachtime. The organic phases were washed twice with 100 ml of water eachtime, dried over magnesium sulfate, filtered and concentrated.Chromatographic purification of the crude product (2.1 g) on silica gelat 0.5 bar with ethyl acetate/petroleum ether (vol. 2:98) andrecrystallization from 20 ml of methanol gave 1.26 g oftrans-4-[trans-4-(4-pentenyl)cyclohexyl]-cyclohexanecarbonitrile ascolorless crystals with m.p. (C-S_(B)) 20.1° C, S_(B) -N 36.9° C., cl.p.(N-I) 54.8° C.

The following compounds can be prepared in an analogous manner:

trans-4-[trans-4-(4Z-Hexenyl)cyclohexyl]cyclohexanecarbonitrile;

trans-4-[trans-4-(4Z-heptenyl)cyclohexyl]cyclohexanecarbonitrile;

trans-4-[trans-4-(4Z-octenyl)cyclohexyl)cyclohexanecarbonitrile;

trans-4-[trans-4-(4Z-nonenyl)cyclohexyl)cyclohexanecarbonitrile;

trans-4-[trans-4-(4Z-decenyl)cyclohexyl]cyclohexanecarbonitrile.

The following compounds can be prepared by reacting the3-[trans-4-(trans-4-cyanocyclohexyl)cyclohexyl]propionaldehyde, obtainedin step g), in an analogous manner to step j) and if necessary E/Zisomerization in an analogous manner to Example 3k):

trans-4-[trans-4-(3-Butenyl)cyclohexyl]cyclohexanecarbonitrile; m.p.(C-N) 50.7° C., cl.p. (N-I) 82.7° C.;

trans-4-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexanecarbonitrile; m.p.(C-N) 79.4° C., cl.p. (N-I) 99.5° C.;

trans-4-[trans-4-(3E-hexenyl)cyclohexyl]cyclohexanecarbonitrile;

trans-4-[trans-4-(3E-heptenyl)cyclohexyl]cyclohexanecarbonitrile;

trans-4-[trans-4-(3E-octenyl)cyclohexyl)cyclohexanecarbonitrile;

trans-4-[trans-4-(3E-nonenyl)cyclohexyl]cyclohexanecarbonitrile;

trans-4-[trans-4-(3E-decenyl)cyclohexyl]cyclohexanecarbonitrile.

The following compounds can be prepared by reacting the4-(4-oxocyclohexyl)benzamide in an analogous manner to steps h) and i),acetalizing the 4-(trans-4-formylcyclohexyl)benzamide, obtained bycrystallization, with ethylene glycol in the presence ofp-toluenesulfonic acid, further reaction of the dioxolane in ananalogous manner to steps c) to g), subsequent Wittig reaction in ananalogous manner to step j) and if necessary E/Z isomerization in ananalogous manner to Example 3k):

trans-4-(trans-4-Vinylcyclohexyl)cyclohexanecarbonitrite;

trans-4-[trans-4-(1E-propenyl)cyclohexyl]cyclohexanecarbonitrile;

trans-4-[trans-4-(1E-butenyl)cyclohexyl]cyclohexanecarbonitrile;

trans-4-[trans-4-(1E-pentenyl)cyclohexyl]cyclohexanecarbonitrile;

trans-4-[trans-4-(1E-hexenyl)cyclohexyl]cyclohexanecarbonitrile:

trans-4-[trans-4-(1E-heptenyl)cyclohexyl]cyclohexanecarbonitrile;

trans-4-[trans-4-(1E-octenyl)cyclohexyl]cyclohexanecarbonitrile;

trans-4-[trans-4-(1E-nonenyl)cyclohexyl]cyclohexanecarbonitrile;

trans-4-[trans-4-(1E-decenyl)cyclohexyl]cyclohexanecarbonitrile.

The following compounds can also be prepared starting from4-[2-(4-oxocyclohexyl)ethyl)benzamide [preparable from the nitriledescribed in Mol. Cryst. Liq. Cryst. 131, 327 (1985)] in an analogousmanner to the above method:

trans-4-[2-(trans-4-(4-Pentenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(4Z-hexenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(4Z-heptenyl)cyclohexyl)ethyl)cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(4Z-octenyl)cyclohexyl)ethyl)cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(4Z-nonenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(4Z-decenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-(2-(trans-4-(3-butenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(3E-pentenyl)cyclohexyl)ethyl)cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(3E-hexenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-(2-(trans-4-(3E-heptenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(3E-octenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-(2-(trans-4-(3E-nonenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(3E-decenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-vinylcyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(1E-propenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(1E-butenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(1E-pentenyl)cyclohexyl)ethyl)cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(1E-hexenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(1E-heptenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(1E-octenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(1E-nonenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile;

trans-4-[2-(trans-4-(1E-decenyl)cyclohexyl)ethyl]cyclohexanecarbonitrile.

EXAMPLE 3

a) A suspension of 109.6 g of 4-(4-nitrophenyl)cyclohexanone (preparableby nitrating 4-phenylcyclohexanone) in 1 1 of dioxan was treated with 50ml of triethylamine and 2 g of 5 percent palladium-charcoal andhydrogenated at room temperature and 0.3 bar hydrogen pressure whilestirring well. After 2 hours the mixture was filtered. The filtrate wasevaporated on a water-jet vacuum at a bath temperature of 30° C. and theevaporation residue was dried at 40° C. overnight in a drying oven undera water-jet vacuum. There were thus obtained 94.5 g of4-(4-amino-phenyl)cyclohexanone as white crystals with m.p. 127°-128° C.

b) 200 ml of 4N sulfuric acid were heated to 80° C. in a sulfonationflask and then treated with about 5% of a solution of 37.9 g of4-(4-aminophenyl)cyclohexanone in 200 ml of 4N sulfuric acid.Subsequently, the remaining solution of 4-(4-aminophenyl)cyclohexanoneas well as a solution of 15.2 g of sodium nitrite in 45 ml of water weresimultaneously added dropwise to the reaction mixture at 80° C. within1.5 hours. Thereafter, the mixture was treated dropwise at 80° C. within30 minutes with a solution of 9 g of sodium nitrite in 27 ml of waterand stirred at 80° C. for a further 1 hour. After cooling the reactionmixture to 0° C. the separated crystals were removed by filtration undersuction, washed with 200 ml of cold water and dried up to constantweight at 60° C. in a drying oven under a water-jet vacuum. Thecrystalline crude product (34.6 g) was suspended in 520 ml of ethylacetate. The suspension was heated to reflux for 1 hour, then treatedwith 1.7 g of active carbon and then heated to reflux for a further 1hour. The mixture was subsequently suction filtered (rinsing with 40 mlof warm ethyl acetate) and the filtrate was evaporated under a water-jetvacuum at a bath temperature of 40° C. Drying of the evaporation residueup to constant weight at 60° C. in a drying oven under a water-jetvacuum gave 32.2 g of 4-(4-hydroxyphenyl)cyclohexanone as yellow-browncrystals with m.p. 165°-166° C.

c) A suspension of 3.8 g of 4-(4-hydroxyphenyl)cyclohexanone in 60 ml oftert.butyl methyl ether was treated in a sulfonation flask under a weakstream of nitrogen with 10.6 g of2-(1,3-dioxolan-2-yl)ethyl-triphenylphosphonium bromide and 2.2 g ofpotassium tert.butylate. The mixture was firstly stirred for 30 minutes,then treated portion wise within 2.25 hours at 25° C. with a further 2.7g of potassium tert.butylate and stirred at room temperature for afurther 1 hour. Thereafter, the reaction mixture was treated with anadditional 1.8 g of 2-(1,3-dioxolan-2-yl)ethyl-triphenylphosphoniumbromide and 0.45 g of potassium tert.butylate and stirred for a further1 hour. Subsequently, the reaction mixture was poured into 80 ml ofwater and acidified with 11 ml of 2N sulfuric acid. The aqueous phasewas separated and extracted twice with 80 ml of tert.butyl methyl ethereach time. The organic phases were washed twice with 50 ml of water eachtime, dried over sodium sulfate and suction filtered. The filtrate wasevaporated up to constant weight under a water-jet vacuum at a bathtemperature of 40° C. The reddish oil obtained (10.9 g) was separated bychromatography on silica gel with toluene and toluene/ tert.butyl methylether (vol. 20:1). Evaporation of the product fractions in a water-jetvacuum and drying the residue up to constant weight in a drying ovenunder a water-jet vacuum at 60° C. finally gave 4.5 g of4-[4-[2-(1,3-dioxolan-2-yl) ethylidene]cyclohexyl]phenol as yellowishcrystals with m.p. 125.5°-126.5° C.

d) A solution of 36.5 g of4-[4-[2-(1,3-dioxolan-2-yl)-ethylidene]cyclohexyl]phenol in 500 ml oftoluene and 50 ml of triethylamine was hydrogenated in a hydrogenationautoclave at 90° C. for 1 hour with 3.2 g of 5 percent platinum-charcoaland 10 bar of hydrogen. The mixture was subsequently suction filteredand the residue was washed with 30 ml of warm toluene. The filtrate wasevaporated up to constant weight under a water-jet vacuum at a bathtemperature of 40° C. The white crystals obtained (37 g) were dissolvedin 180 ml of methanol while heating. The solution was left to cool toroom temperature and then placed in a refrigerator for 5 hours. Thecrystals were subsequently removed by filtration under suction, washedwith 50 ml of cold methanol and dried at 60° C. in a drying oven under awater-jet vacuum. There were thus obtained 27.6 g of4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]phenol as whitecrystals with m.p. 153.5°-154.50° C.

e) A mixture of 100 g of4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl)phenol, 10 g of 5percent rhodium/aluminium oxide and 1 1 of ethyl acetate washydrogenated in a steel stirring autoclave with 50 bar of hydrogen at80° C. for 90 minutes. The catalyst was then removed by filtration undersuction and washed with 100 ml of ethyl acetate. The filtrate wasevaporated and the residue was dried at 25° C./0.4 mbar. There were thusobtained 101.75 g of4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl)cyclohexyl]cyclohexanolcontaining 59% of cis isomer and 36% of trans isomer.

f) A solution of 12.9 g of pyridinium chlorochromate in 80 ml ofmethylene chloride was treated dropwise within 5 minutes at roomtemperature while gassing with nitrogen with a solution of 13.0 g of4-[trans-4-[2-(1.3-dioxolan-2-yl)ethyl]cyclohexyl]cyclohexanol in 40 mlof methylene chloride. The mixture was stirred for a further 1 hour,then diluted with 100 ml of diethyl ether and filtered and the filtratewas evaporated. The evaporation residue was taken up in 200 ml ofdiethyl ether, the mixture was filtered, the filtrate was evaporated andthen this procedure was repeated twice more. Thereafter; the brownishsolid mass obtained (12.1 g) was separated by chromatography on silicagel with ethyl acetate/petroleum ether (vol. 1:4). Crystallization ofthe colorless ketone fraction from 60 ml of ethyl acetate and 200 ml ofpetroleum ether finally gave 7.0 g of pure4-[trans-4-[2-(1,3-dioxolan-2-yl) ethyl]cyclohexyl]cyclohexanone.

g) A suspension of 2.97 g of sodium borohydride in 300 ml of isopropanolwas treated dropwise while gassing with nitrogen at -70° C. with asolution of 11 g of 4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]cyclohexanone in 200 ml of isopropanol. After about 1hour the reaction mixture was left to warm to room temperature, dilutedwith 500 ml of 0.1N hydrochloric acid and extracted three times with 300ml of methylene chloride each time. The organic phases were washed withwater, dried over magnesium sulfate, filtered and evaporated.Crystallization of the residue (11 g) from 500 ml of ethylacetate/petroleum ether (vol. 3:5) gave 6.6 g of puretrans-4-[trans-4-[2-(1,3-dioxolan-2-yl) ethyl]cyclohexyl]cyclohexanolwith m.p. 129.5° C.

h) 2.04 g of sodium hydride as an about 50 percent oily suspension wereplaced in a round flask while gassing with nitrogen and washed twicewith pentane. Then, 40 ml of dry tetrahydrofuran and a solution of 6.0 gof trans-4-[trans-4-[2-(1,3-dioxolan-2-yl) ethyl)cyclohexyl]cyclohexanolin 30 ml of tetrahydrofuran were added to the sodium hydride. Themixture was stirred at room temperature for 30 minutes, then treatedwith 4.0 ml of methyl iodide and heated to reflux for 2 hours.Subsequently, the reaction mixture was cooled, taken up in 200 ml ofdiethyl ethyl and washed three times with 200 ml of water each time. Theorganic phase was dried over magnesium sulfate, filtered and evaporated,whereby there were obtained 6.3 g of2-[2-[trans-4-(trans-4-methoxycyclohexyl)cyclohexyl)ethyl]-1,3-dioxolane with m.p. 74° C.

i) 6.2 g of2-[2-[trans-4-(trans-4-methoxycyclohexyl)-cyclohexyl]ethyl]-1,3-dioxolanewere treated with 100 ml of water, 50 ml of glacial acetic acid and 20ml of dioxan while gassing with nitrogen. The mixture was stirred at100° C. (bath temperature) for 1.5 hours, then neutralized with dilutesodium hydrogen carbonate solution and extracted three times withdiethyl ether. The combined ether phases were washed once with water andtwice with dilute sodium hydrogen carbonate solution, dried overmagnesium sulfate, filtered and evaporated. Recrystallization of thecrude aldehyde obtained (4.34 g) from 150 ml of petroleum ether at -20°C. gave 2.8 g of 3-[trans-4-(trans-4-methoxycyclohexyl)cyclohexyl]propionaldehyde in a purity of 96%.

j) 2.65 g of ethyltriphenylphosphonium bromide were suspended in 40 mlof tert.butyl methyl ether while gassing with argon. The suspension wastreated at room temperature with 797 mg of potassium tert.butylate andstirred for 1 hour. The mixture was subsequently cooled to 0° C.,treated dropwise within 3 minutes with a solution of 1.1 g of3-[trans-4-(trans-4-methoxycyclohexyl)cyclohexyl]propionaldehyde in 15ml of tert.butyl methyl ether and then left to warm slowly to roomtemperature while stirring. After 2 hours the pale yellow suspension waspartitioned in diethyl ether/water. The aqueous phase was separated andwashed three times diethyl ether. The organic phases were washed twicewith water, dried over magnesium sulfate, filtered and evaporated.Chromatographic purification of the yellow, solid crude product onsilica gel with ethyl acetate/petroleum ether (vol. 3:97) gave 0.91 g oftrans-4-(3-pentenyl)-l-(trans-4-methoxycyclohexyl)cyclohexane with a Z/Eratio of 86:11.

k) 0.91 g oftrans-4-(3-pentenyl)-l-(trans-4-methoxycyclohexyl)cyclohexane(Z/E=86:11) was treated with 6 ml of toluene, 0.11 g of sodiumbenzenesulfinate and 1 ml of 1N hydrochloric acid while gassing withnitrogen. The mixture was stirred at 50° C. for 15 hours, then pouredinto 100 ml of dilute sodium hydrogen carbonate solution and extractedthree times with 50 ml of diethyl ether each time. The combined organicphases were washed with 100 ml of dilute sodium carbonate solution andwith 100 ml of water, dried over magnesium sulfate, filtered andevaporated. The yellowish oil obtained (0.9 g) was purified bychromatography on silver nitrate-impregnated silica gel with diethylether/hexane (vol. 1:9). Recrystallization of the product obtained (486mg) from 10 ml of methanol at -20° C. gave puretrans-4-(3E-pentenyl)-1-(trans-4-methoxycyclohexyl) cyclohexane withm.p. (C-N) 16.6° C. and cl.p. (N-I) 43.7° C.

The following compounds can be prepared in an analogous manner:

trans-4-(3-Butenyl)-1-(trans-4-methoxycyclohexyl)-cyclohexane, m.p.(C-N) -13.6° C., cl.p. (N-I) 18.0° C.;

trans-4-(3-butenyl)-1-(trans-4-ethoxycyclohexyl)-cyclohexane, m.p. (C-N)13.1° C., cl.p. (N-I) 45.3° C.;

trans-4-(3-butenyl)-1-(trans-4-propyloxycyclohexyl)-cyclohexane;

trans-4-(3-butenyl)-1-(trans-4-butyloxycyclohexyl)-cyclohexane;

trans-4-(3-butenyl)-1-(trans-4-pentyloxycyclohexyl)-cyclohexane;

trans-4-(3-butenyl)-1-(trans-4-hexyloxycyclohexyl)-cyclohexane;

trans-4-(3E-pentenyl)-1-(trans-4-ethoxycyclohexyl)-cyclohexane, m.p.(C-N) 44.5° C. cl.p. (N-I) 76.5° C.;

trans-4-(3E-pentenyl)-1-(trans-4-propyloxycyclohexyl)-cyclohexane;

trans-4-(3E-pentenyl)-1-(trans-4-butyloxycyclohexyl)-cyclohexane;

trans-4-(3E-pentenyl)-1-(trans-4-pentyloxycyclohexyl)-cyclohexane;

trans-4-(3E-pentenyl)-1-(trans-4-hexyloxycyclohexyl)-cyclohexane;

trans-4-(3E-hexenyl)-1-(trans-4-methoxycyclohexyl)-cyclohexane;

trans-4-(3E-hexenyl)-1-(trans-4-ethoxycyclohexyl)-cyclohexane;

trans-4-(3E-hexenyl)-1-(trans-4-propyloxycyclohexyl)-cyclohexane;

trans-4-(3E-hexenyl)-1-(trans-4-butyloxycyclohexyl)-cyclohexane;

trans-4-(3E-hexenyl)-1-(trans-4-pentyloxycyclohexyl)-cyclohexane;

trans-4-(3E-hexenyl)-1-(trans-4-hexyloxycyclohexyl)-cyclohexane.

The following compounds can be prepared in an analogous manner to stepsa) to i) and further reaction of the propionaldehyde obtained in ananalogous manner to Example 2, steps h), i) and j):

trans-4-(4-Pentenyl)-1-(trans-4-methoxycyclohexyl)-cyclohexane, m.p.(C-S_(B)) 7.7° C. cl.p. (S_(B) -1) 14.0° C.;

trans-4-(4-pentenyl)-1-(trans-4-ethoxycyclohexyl)-cyclohexane, m.p.(C-S_(B)) 10.5° C. cl.p. (S_(B) -I) 43.1° C;

trans-4-(4-pentenyl)-1-(trans-4-propyloxycyclohexyl)-cyclohexane:

trans-4-(4-pentenyl)-1-(trans-4-butyloxycyclohexyl)-cyclohexane;

trans-4-(4-pentenyl)-1-(trans-4-pentyloxycyclohexyl)-cyclohexane;

trans-4-(4-pentenyl)-1-(trans-4-hexyloxycyclohexyl)-cyclohexane;

trans-4-(4Z-hexenyl)-1-(trans-4-methoxycyclohexyl)-cyclohexane;

trans-4-(4Z-hexenyl)-1-(trans-4-ethoxycyclohexyl)-cyclohexane;

trans-4-(4Z-hexenyl)-1-(trans-4-propyloxycyclohexyl)-cyclohexane;

trans-4-(4Z-hexenyl)-1-(trans-4-butyloxycyclohexyl)-cyclohexane;

trans-4-(4Z-hexenyl)-1-(trans-4-pentyloxycyclohexyl)-cyclohexane;

trans-4-(4Z-hexenyl)-1-(trans-4-hexyloxycyclohexyl)-cyclohexane.

The following compounds can be prepared by reacting the4-(4-hydroxyphenyl)cyclohexanone (step b) in an analogous manner toExample 2, steps h) and i), acetalizing the4-(trans-4-formylcyclohexyl)phenol obtained with ethylene glycol in thepresence of p-toluenesulfonic acid and further reacting the dioxolane inan analogous manner to the previous steps e) to k):

trans-4-Vinyl-1-(trans-4-methoxycyclohexyl)-cyclohexane;

trans-4-vinyl-1-(trans-4-ethoxycyclohexyl)-cyclohexane;

trans-4-vinyl-1-(trans-4-propyloxycyclohexyl)-cyclohexane;

trans-4-vinyl-1-(trans-4-butyloxycyclohexyl)-cyclohexane;

trans-4-vinyl-1-(trans-4-pentyloxycyclohexyl)-cyclohexane;

trans-4-vinyl-1-(trans-4-hexyloxycyclohexyl)-cyclohexane;

trans-4-(1E-propenyl)-1-(trans-4-methoxycyclohexyl)-cyclohexane;

trans-4-(1E-propenyl)-1-(trans-4-ethoxycyclohexyl)-cyclohexane;

trans-4-(1E-propenyl)-1-(trans-4-propyloxycyclohexyl)-cyclohexane;

trans-4-(1E-propenyl)-1-(trans-4-butyloxycyclohexyl)-cyclohexane;

trans-4-(1E-propenyl)-1-(trans-4-pentyloxycyclohexyl)-cyclohexane;

trans-4-(1E-propenyl)-1-(trans-4-hexyloxycyclohexyl))-cyclohexane;

trans-4-(1E-butenyl)-1-(trans-4-methoxycyclohexyl)-cyclohexane;

trans-4-(1E-butenyl)-1-(trans-4-ethoxycyclohexyl)-cyclohexane;

trans-4-(1E-butenyl)-1-(trans-4-propyloxycyclohexyl)-cyclohexane;

trans-4-(1E-butenyl)-1-(trans-4-butyloxycyclohexyl)-cyclohexane;

trans-4-(1E-butenyl)-1-(trans-4-pentyloxycyclohexyl)-cyclohexane;

trans-4-(1E-pentenyl)-1-(trans-4-methoxycyclohexyl)-cyclohexane;

trans-4-(1E-pentenyl)-1-(trans-4-ethoxycyclohexyl)-cyclohexane;

trans-4-(1E-pentenyl)-1-(trans-4-propyloxycyclohexyl)-cyclohexane;

trans-4-(1E-pentenyl)-1-(trans-4-butyloxycyclohexyl)-cyclohexane.

The following compounds can also be prepared according to the abovemethod starting from 4-(2-phenyl-ethyl)-cyclohexanone (preparable in ananalogous manner to the nitrile described in Mol. Cryst. Liq. Cryst.131, 327 (1985)]:

4-[2-[trans-4-(2-(1,3-Dioxolan-2-yl)-ethyl)cyclohexyl]-ethyl]cyclohexanone;

trans-4-(3-butenyl)-1-[2-(trans-4-methoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3-butenyl)-1-[2-(trans-4-ethoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3-butenyl)-1-[2-(trans-4-propyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3-butenyl)-1-(2-(trans-4-butyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3-butenyl)-1-[2-(trans-4-pentyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3-butenyl)-1-[2-(trans-4-hexyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3E-pentenyl)-1-[2-(trans-4-methoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3E-pentenyl)-1-[2-(trans-4-ethoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3E-pentenyl)-1-[2-(trans-4-propyloxycyclohexyl)ethyl]cyclohexane;

trans-4-(3E-pentenyl)-1-[2-(trans-4-butyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3E-pentenyl)-1-[2-(trans-4-pentyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3E-pentenyl)-1-[2-(trans-4-hexyloxycyclohexyl)-ethyl)cyclohexane;

trans-4-(3E-hexenyl)-1-[2-(trans-4-methoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3E-hexenyl)-1-[2-(trans-4-ethoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3E-hexenyl)-1-[2-(trans-4-propyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3E-hexenyl)-1-[2-(trans-4-butyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3E-hexenyl)-1-[2-(trans-4-pentyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(3E-hexenyl)-1-[2-(trans-4-hexyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(4-pentenyl)-1-[2-(trans-4-methoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(4-pentenyl)-1-[2-(trans-4-ethoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(4-pentenyl)-1-[2-(trans-4-propyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(4-pentenyl)-1-[2-(trans-4-butyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(4-pentenyl)-1-[2-(trans-4-pentyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(4-pentenyl)-1-(2-(trans-4-hexyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(4Z-hexenyl)-1-[2-(trans-4-methoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(4Z-hexenyl)-1-[2-(trans-4-ethoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(4Z-hexenyl)-1-[2-(trans-4-propyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(4Z-hexenyl)-1-[2-(trans-4-butyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-vinyl-1-[2-(trans-4-methoxycyclohexyl)ethyl]-cyclohexane;

trans-4-vinyl-1-[2-(trans-4-ethoxycyclohexyl)ethyl]-cyclohexane;

trans-4-vinyl-1-[2-(trans-4-propyloxycyclohexyl)ethyl]-cyclohexane;

trans-4-vinyl-1-[2-(trans-4-butyloxycyclohexyl)ethyl]-cyclohexane;

trans-4-vinyl-1-[2-(trans-4-pentyloxycyclohexyl)ethyl]-cyclohexane;

trans-4-vinyl-1-(2-(trans-4-hexyloxycyclohexyl)ethyl]-cyclohexane;

trans-4-(1E-propenyl)-1-[2-(trans-4-methoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(1E-propenyl)-1-[2-(trans-4-ethoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(1E-propenyl)-1-[2-(trans-4-propyloxycyclohexyl)ethyl]cyclohexane;

trans-4-(1E-propenyl)-1-[2-(trans-4-butyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(1E-propenyl)-1-(2-(trans-4-pentyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(1E-propenyl)-1-[2-(trans-4-hexyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(1E-butenyl)-1-[2-(trans-4-methoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(1E-butenyl)-1-[2-(trans-4-ethoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(1E-butenyl)-1-[2-(trans-4-propyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(1E-butenyl)-1-[2-(trans-4-butyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(1E-butenyl)-1-[2-(trans-4-pentyloxycyclohexyl)-ethyl]cyclohexane;

trans-4-(1E-pentenyl)-1-[2-(trans-4-methoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(1E-pentenyl)-1-[2-(trans-4-ethoxycyclohexyl)-ethyl]cyclohexane;

trans-4-(1E-pentenyl)-1-[2-(trans-4-propyloxycyclohexyl)-ethyl]cyclohexane:

trans-4-(1E-pentenyl)-1-[2-(trans-4-butyloxycyclohexyl)-ethyl]cyclohexane.

EXAMPLE 4

a) A Grignard solution from 3.59 g of magnesium and 16.75 ml of1-bromo-4-fluorobenzene in 70 ml of tetrahydrofuran was treated dropwiseat 0° C. within 30 minutes with a solution of 33.1 g of4-(trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]cyclohexanone(prepared according to Example 3) in 90 ml of tetrahydrofuran. Thereaction mixture was stirred at room temperature for a further 4 hoursand then heated to boiling for 1.5 hours. Subsequently, the reactionmixture was left to cool, diluted with 100 ml of diethyl ether andwashed with 80 ml of semi-saturated ammonium chloride solution. Theaqueous phase was back-extracted with 100 ml of diethyl ether. Thecombined organic phases were washed three times with 60 ml of saturatedsodium chloride solution each time, dried over sodium sulfate. filteredand evaporated. There were thus obtained 41.0 g of crude1-[4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]-1-hydroxycyclohexyl]-4-fluorobenzene.

b) A solution of 41.0 g of crude I-[4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]-1-hydroxycyclohexyl]-4-fluorobenzene in 225 ml ofm-xylene was treated with 15 g of potassium hydrogen sulfate and themixture was heated to boiling for 11 hours while stirring. After coolingthe salt was removed by filtration. The filtrate was diluted with 250 mlof diethyl ether, washed with 200 ml of saturated sodium hydrogencarbonate solution and washed twice with 150 ml of water each time,dried over sodium sulfate and concentrated. There were thus obtained30.3 g of crude 1-[4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)cyclohexyl]-1-cyclohexenyl]-4-fluorobenzene.

c) A solution of 31.5 g of crude 1-[4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]-1-cyclohexenyl]-4-fluorobenzene and 0.5 ml oftriethylamine in 1 1 of toluene was hydrogenated at room temperature andnormal pressure with 4.5 g of 5 percent palladium-charcoal until thehydrogen uptake came to a standstill. The catalyst was removed byfiltration and the filtrate was evaporated. For the isomerization, theresulting1-[4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)-cyclohexyl]cyclohexyl]-4-fluorobenzene (31.1 g; cis/trans ratio about 1:1) was treated with asolution of 10.0 g of potassium tert.butylate in 310 ml ofN,N-dimethylformamide and heated to 105° C. for 23 hours. Subsequently,the reaction mixture was poured on to 400 g of ice and 100 ml ofsaturated sodium hydrogen carbonate solution. The mixture was extractedonce with 500 ml of diethyl ether and twice with 250 ml of diethyl ethereach time. The organic phases were washed three times with 200 ml ofwater each time, dried over sodium sulfate, filtered and evaporated.There were thus obtained 30.5 g of predominantly solid1-[trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)cyclohexyl]cyclohexyl)-4-fluorobenzene which was further processed withoutadditional purification.

The following compounds can be prepared in an analogous manner:

1-[trans-4-[trans-4-(2-(1,3-Dioxolan-2-yl)ethyl)cyclohexyl]cyclohexyl)-3,4-difluorobenzene;

1-[trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)cyclohexyl]cyclohexyl]-3-chloro-4-fluorobenzene;

1-[trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)cyclohexyl)cyclohexyl]-3-fluoro-4-chlorobenzene;

1-[trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)cyclohexyl]cyclohexyl]-4-chlorobenzene;

1-[trans-4-[2-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)-cyclohexyl]ethyl]cyclohexyl)-4-fluorobenzene;

1-[trans-4-[2-(trans-4-(2-(1,3-dioxolan-2-yl)ethyl)-cyclohexyl]ethyl]cyclohexyl]-3,4-difluorobenzene;

1-[trans-4-[2-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)-cyclohexyl]ethyl)cyclohexyl]-3-chloro-4-fluorobenzene;

1-[trans-4-[2-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)-cyclohexyl]ethyl)cyclohexyl]-4-chlorobenzene;

1-[trans-4-[2-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)-cyclohexyl]ethyl]cyclohexyl]-3-fluoro-4-chlorobenzene.

EXAMPLE 5

a) A solution of 3.1 g oftrans-4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]cyclohexanecarboxylic acid (prepared according to Example 2) in 50 mlof dry diethyl ether is treated at 0° C. with 380 mg of lithiumaluminium hydride and then heated to reflux for 4 hours. Thereafter, thereaction mixture is cooled, treated with ice-water and ammonium chloridesolution and extracted with diethyl ether. The organic phase is washedwith water, dried over magnesium sulfate, filtered and evaporated. Theresulting crude product of[trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)-ethyl)cyclohexyl]cyclohexyl]methanolis used without additional purification.

b) A solution of 2.96 g of crude(trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)cyclohexyl]cyclohexyl]methanol in 20 ml of dry pyridine is treated at 0° C. with 2.1 g ofp-toluenesulfonyl chloride. The mixture is stirred at room temperaturefor 15 hours, then diluted with 200 ml of methylene chloride and washedseveral times with water. The organic phase is dried over magnesiumsulfate, filtered and evaporated. Chromatographic purification of theresulting crude product on silica gel with ethyl acetate/petroleum ether(vol. 1:9) gives [trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]cyclohexyl]methyl p-toluenesulfonate.

c) A solution of 0.33 g of potassium hydroxide in 7 ml of 95 percentethanol is treated with 1.12 g of p-fluorophenol. Thereafter, themixture is treated with a solution of 2.26 g of[trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)-ethyl)cyclohexyl]cyclohexyl)methylp-toluenesulfonate in 23 ml of ethanol and stirred at 80° C. (bathtemperature) for 24 hours. Subsequently, the reaction mixture ispartitioned in 1N hydrochloric acid and methylene chloride. The organicphase is washed several times with water, dried over magnesium sulfate,filtered and evaporated. Chromatographic purification of the resultingcrude product on silica gel with ethyl acetate/petroleum ether gives1-[[trans-4-(trans-4-(2-(1,3-dioxolan-2-yl)-ethyl)cyclohexyl]cyclohexyl]methoxy]-4-fluorobenzene.

The following compounds can be prepared in an analogous manner:

1-[[trans-4-(trans-4-(2-(1,3-Dioxolan-2-yl)-ethyl)cyclohexyl)cyclohexyl]methoxy)-3,4-difluorobenzene;

1-[[trans-4-(trans-4-(2-(1,3-dioxolan-2-yl)-ethyl)cyclohexyl)cyclohexyl]methoxy]-3-chloro-4-fluorobenzene;

1-[[trans-4-(trans-4-(2-(1,3-dioxolan-2-yl)-ethyl)cyclohexyl)cyclohexyl]methoxy]-4-chlorobenzene;

1-[[trans-4-(trans-4-(2-(1,3-dioxolan-2-yl)-ethyl)cyclohexyl)cyclohexyl]methoxy]-3-fluoro-4-chlorobenzene.

EXAMPLE 6

a) A solution of 3.1 g of pyridinium chlorochromate in 20 ml ofmethylene chloride is treated dropwise at room temperature with asolution of 3 g of[trans-4-(trans-4-(2-(1,3-dioxolan-2-yl)ethyl)cyclohexyl]cyclohexyl]methanol (preparable according to Example 5) in 10 ml ofmethylene chloride. The mixture is stirred for a further 1 hour, thendiluted with 50 ml of diethyl ether and filtered. The filtrate isevaporated, the evaporation residue is taken up in 50 ml of diethylether and the solution obtained is again filtered. Chromatographicpurification on silica gel with ethyl acetate/hexane finally givestrans-4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]cyclohexanecarboxaldehyde. aldehyde.

b) 3 g of p-fluorobenzyl-triphenylphosphonium bromide (preparable fromp-fluorobenzyl bromide and triphenylphosphine) are suspended in 50 ml oftert.butyl methyl ether. The suspension is treated at room temperaturewith 0.75 g of potassium tert.butylate and stirred for 1.5 hours.Subsequently, the mixture is treated dropwise at 0° C. within 5 minuteswith a solution of 1.40 g oftrans-4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]-cyclohexanecarboxaldehydein 25 ml of tert.butyl methyl ether and stirred at room temperature fora further 24 hours. Thereafter, the reaction mixture is taken up diethylether, washed several times with water, dried over magnesium sulfate,filtered and concentrated. Chromatographic purification of the resultingcrude product on silica gel with ethyl acetate/petroleum ether (vol.3:97) givesβ-[trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)-cyclohexyl]cyclohexyl]-4-fluorostyrene.

c) A solution of 1 g ofβ-[trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)cyclohexyl]cyclohexyl]-4-fluorostyrene in 10 ml of toluene and 5 ml of ethanol ishydrogenated with 500 mg of 5 percent palladium-charcoal at roomtemperature and normal pressure until the hydrogen uptake comes to astandstill. The black suspension is subsequently filtered. Evaporationof the filtrate gives1-[2-[trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)cyclohexyl]cyclohexyl]ethyl]-4-fluorobenzene.

The following compounds can be prepared in an analogous manner:

1-[2-[trans-4-[trans-4-(2-(1,3-Dioxolan-2-yl)ethyl)-cyclohexyl]cyclohexyl)ethyl]-3,4-difluorobenzene;

1-[2-(trans-4-[trans-4-(2-(1,3-dioxolarn-2-yl)ethyl)-cyclohexyl]cyclohexyl)ethyl]-3-chloro-4-fluorobenzene;

1-[2-[trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)-cyclohexyl]cyclohexyl]ethyl]-4-chlorobenzene;

1-[2-(trans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)-cyclohexyl]cyclohexyl]ethyl]-3-fluoro-4-chlorobenzene.

EXAMPLE 7

A solution of 1.7 g of 4-fluorobenzoyl chloride in 5 ml of pyridine istreated with 2.8 g oftrans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)cyclohexyl]-cyclohexanol(prepared according to Example 3) and stirred at room temperature for 12hours. Thereafter, the reaction mixture is poured on to ice-water andextracted three times with diethyl ether. The organic phases are washedin succession with saturated sodium hydrogen carbonate solution, with 10percent hydrochloric acid, with saturated sodium hydrogen carbonatesolution and with water, then dried over magnesium sulfate, filtered andconcentrated. Chromatographic purification of the resulting crudeproduct-on silica gel with ethyl acetate/petroleum ether (vol. 3:97)gives 4-fluorobenzoic acidtrans-4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]-cyclohexylester.

The following compounds can be prepared in an analogous manner:

3,4-Difluorobenzoic acidtrans-4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]cyclohexylester;

3-chloro-4-fluorobenzoic acidtrans-4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl ]cyclohexylester;

4-chlorobenzoic acidtrans-4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]cyclohexylester;

3-fluoro-4-chlorobenzoic acidtrans-4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl ]cyclohexylester.

EXAMPLE 8

2.04 g of sodium hydride as an about 50% oily suspension are placedunder nitrogen gasification and washed twice with pentane. There arethen added to the sodium hydride 40 ml of dry tetrahydrofuran and asolution of 6.0 g oftrans-4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]-cyclohexyl]cyclohexanol(prepared according to Example 2) in 30 ml of tetrahydrofuran. Themixture is stirred at room temperature for 30 minutes, then treated with6.03 g of 4-fluorobenzyl bromide and heated to reflux for 2 hours.Subsequently, the reaction mixture is cooled, taken up in 200 ml ofdiethyl ether and washed three times with 200 ml of water each time. Theorganic phase is dried over magnesium sulfate, filtered and evaporated,whereby there is obtainedtrans-4-[trans-4-[2-(1,3-dioxolan-2-yl)-ethyl]cyclohexyl]cyclohexyl4-fluorobenzyl ether.

The following compounds can be prepared in an analogous manner:

trans-4-[trans-4-[2-(1,3-Dioxolan-Z-yl)ethyl]cyclohexyl]cyclohexyl3,4-difluorobenzyl ether;

trans-4-[trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl)cyclohexyl3-chloro-4-fluorobenzyl ether;

trans-4-[trans-4-[2-(1,3-dioxolan-Z-yl)ethyl]cyclohexyl]cyclohexyl4-chlorobenzyl ether;

trans-4-(trans-4-[2-(1,3-dioxolan-2-yl)ethyl]cyclohexyl]cyclohexyl3-fluoro-4-chlorobenzyl ether.

EXAMPLE 9

a) A mixture of 29.1 g of crude1-ftrans-4-[trans-4-(2-(1,3-dioxolan-2-yl)ethyl)cyclohexyl]cyclohexyl]-4-fluorobenzene, 200 ml of dioxan, 200 ml of glacial aceticacid and 400 ml of water was heated to slight boiling (bath temperature115° C.) for 5 hours while stirring and gassing with nitrogen. Thereaction mixture was then poured on to 500 g of ice. The aqueous phasewas separated and extracted three times with 400 ml of diethyl ethereach time. The combined organic phases were washed with 500 ml ofsaturated sodium hydrogen carbonate solution and with 500 ml of water,dried over sodium sulfate, filtered and concentrated. There were thusobtained 25.2 g of crude, solid3-[trans-4-[trans-4-(4-fluorophenyl)cyclohexyl]-cyclohexyl]propionaldehyde.

b) A suspension of 9.1 g of methoxymethyl-triphenylphosphonium chloridein 50 ml of diethyl ether was treated with 2.85 g of potassiumtert.butylate while gassing with nitrogen. The red suspension wasstirred at room temperature for a further 30 minutes and then treateddropwise at 0° C. with a solution of 5.43 g of crude3-(trans-4-[trans-4-(4-fluorophenyl)cyclohexyl]cyclohexyl]propionaldehyde in 30 ml of dry diethyl ether. The reactionmixture was stirred at room temperature for a further 90 minutes, thenpoured into 300 ml of hexane and filtered. Chromatographic purificationof the concentrated filtrate on silica gel with hexane gave 4.9 g ofsolid1-(trans-4-(trans-4-(4-methoxy-3-butenyl)cyclohexyl]cyclohexyl]-4-fluorobenzene.

c) A mixture of 2.48 g ofI-(trans-4-(trans-4-(4-methoxy-3-butenyl)cyclohexyl]cyclohexyl]-4-fluorobenzene, 30 ml of dioxan, 20 ml of glacial acetic acid and 40 mlof water was heated to slight boiling (bath temperature 115° C.) whilestirring and gassing with nitrogen. After cooling the suspension wasdiluted with 70 ml of water. The aqueous phase was separated andextracted three times with 80 ml of diethyl ether each time. Thecombined organic phases were washed twice with 1000 ml of water eachtime, dried over sodium sulfate, filtered and concentrated. There werethus obtained 2.3 g of solid4-(trans-4-[trans-4-(4-fluorophenyl)cyclohexyl]cyclohexyl]butyraldehyde.

d) A suspension of 5.19 g of methyl-triphenylphosphonium bromide in 80ml of diethyl ether was treated with 1.55 g of potassium tert.butylatewhile gassing with nitrogen. The yellow suspension was stirred at roomtemperature for a further 45 minutes and then treated dropwise at 0° C.with a solution of 2.3 g of4-[trans-4-(trans-4-(4-fluorophenyl)cyclohexyl]cyclohexyl]butyraldehyde.The reaction mixture was stirred at 0° C. for a further 2 hours and thendiluted with 60 ml of water. The aqueous phase was separated andextracted twice with 60 ml of hexane each time. The combined organicphases were washed neutral with water, dried over sodium sulfate,filtered and concentrated. Chromatographic purification of the residueon silica gel with hexane gave 1.89 g of crude product. After two-foldrecrystallization from acetone at -20° C. there were obtained 1.22 g of1-[trans-4-[trans-4-(4-pentenyl)-cyclohexyllcyclohexyl]-4-fluorobenzenewith m.p. (C-N) 65.7° C. and cl.p. (N-I) 129.7° C.

The 4-alkenyl compounds named in Example 1 as well as the followingcompounds can be prepared in an analogous manner:

1-[trans-4-[trans-4-(4-Pentenyl)cyclohexyl]cyclohexyl-3,4-difluorobenzene;

1-[trans-4-[trans-4-(4-pentenyl)cyclohexyllcyclohexyl-3-chloro-4-fluorobenzene:

1-[trans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexyl-4-chlorobenzene;

1-[trans-4-[trans-4-(4-pentenyl)cyclohexyl)cyclohexyl-3-fluoro-4-chlorobenzene:

1-[trans-4-[2-(trans-4-(4-pentenyl)cyclohexyl)ethyl]-cyclohexyl]-4-fluorobenzene;

1-[trans-4-[2-(trans-4-(4-pentenyl)cyclohexyl)ethyl]-cyclohexyl]-3,4-difluorobenzene;

1-[trans-4-[2-(trans-4-(4-pentenyl)cyclohexyl)ethyl]-cyclohexyl]-3-chloro-4-fluorobenzene;

1-[trans-4-[2-(trans-4-(4-pentenyl)cyclohexyl)ethyl]-cyclohexyl]-4-chlorobenzene:

1-[trans-4-[2-(trans-4-(4-pentenyl)cyclohexyl)ethyl]-cyclohexyl]-3-fluoro-4-chlorobenzene;

1-[[trans-4-(trans-4-(4-pentenyl)cyclohexyl)cyclohexyl]-methoxy]-4-fluorobenzene;

1-[[trans-4-(trans-4-(4-pentenyl)cyclohexyl)cyclohexyl]-methoxy]-3,4-difluorobenzene:

1-[[trans-4-(trans-4-(4-pentenyl)cyclohexyl)cyclohexyl]-methoxy]-3-chloro-4-fluorobenzene:

1-[[trans-4-(trans-4-(4-pentenyl)cyclohexyl)cyclohexyl]-methoxy]-4-chlorobenzene;

1-[[trans-4-(trans-4-(4-pentenyl)cyclohexyl)cyclohexyl]-methoxy]-3-fluoro-4-chlorobenzene;

1-[2-[trans-4-(trans-4-(4-pentenyl)cyclohexyl)cyclohexyl]ethyl]-4-fluorobenzene;m.p. (C-S_(B)) 7.1° C., phase transition (S_(B) -N) 93° C., cl.p. (N-I)116.6° C.;

1-[2-[trans-4-(trans-4-(4-pentenyl)cyclohexyl)cyclohexyl]ethyl]-3,4-difluorobenzene;

1-[2-[trans-4-(trans-4-(4-pentenyl)cyclohexyl)cyclohexyl]ethyl]-3-chloro-4-fluorobenzene;

1-[2-[trans-4-(trans-4-(4-pentenyl)cyclohexyl)cyclohexyl]ethyl]-4-chlorobenzene:

1-[2-[trans-4-(trans-4-(4-pentenyl)cyclohexyl)cyclohexyl]ethyl]-3-fluoro-4-chlorobenzene;

4-fluorobenzoic acid trans-4-(trans-4-(4-pentenyl)-cyclohexyl]cyclohexylester;

3,4-difluorobenzoic acidtrans-4-(trans-4-(4-pentenyl)cyclohexyl]cyclohexyl ester;

3-chloro-4-fluorobenzoic acidtrans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexyl ester;

4-chlorobenzoic acid trans-4-[trans-4-(4-pentenyl)-cyclohexyl]cyclohexylester;

3-fluoro-4-chlorobenzoic acidtrans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexyl ester;

trans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexyl 4-fluorobenzyl ether;

trans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexyl 3,4-difluorobenzylether;

trans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexyl3-chloro-4-fluorobenzyl ether;

trans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexyl 4-chlorobenzyl ether;

trans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexyl3-fluoro-4-chlorobenzyl ether;

1-[trans-4-[trans-4-(4Z-hexenyl)cyclohexyl]cyclohexyl]-4-fluorobenzene;

1-[trans-4-[trans-4-(4Z-hexenyl)cyclohexyl]cyclohexyl]-3,4-difluorobenzene;

1-[trans-4-(2-(trans-4-(4Z-hexenyl)cyclohexyl)ethyl]-cyclohexyl]-4-fluorobenzene:

1-[trans-4-[2-(trans-4-(4Z-hexenyl)cyclohexyl)ethyl]-cyclohexyl]-3,4-difluorobenzene;

1-[[trans-4-(trans-4-(4Z-hexenyl)cyclohexyl)cyclohexyl]-methoxy]-4-fluorobenzene;

1-[[trans-4-(trans-4-(4Z-hexenyl)cyclohexyl)cyclohexyl]-methoxy]-3,4-difluorobenzene;

1-[2-[trans-4- (trans-4-(4Z-hexenyl)cyclohexyl)cyclohexyl]ethyl]-4-fluorobenzene;

1-[2-[trans-4-(trans-4-(4Z-hexenyl)cyclohexyl)cyclohexyl]ethyl]-3,4-difluorobenzene;

4-fluorobenzoic acid trans-4-(trans-4-(4Z-hexenyl)-cyclohexyl]cyclohexylester;

3,4-difluorobenzoic acidtrans-4-(trans-4-(4Z-hexenyl)cyclohexyl]cyclohexyl ester;

trans-4-(trans-4-(4Z-hexenyl)cyclohexyl]cyclohexyl 4-fluorobenzyl ether;

trans-4-(trans-4-(4Z-hexenyl)cyclohexyl]cyclohexyl 3,4-difluorobenzylether;

The 3E-alkenyl compounds named in Example 1 as well as the followingcompounds can also be prepared in an analogous manner by omitting stepsb) and c):

1-[trans-4-[trans-4-(3-Butenyl)cyclohexyl]cyclohexyl-3,4-difluorobenzene:

1-[trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexyl-3-chloro-4-fluorobenzene:

1-[trans-4-[trans-4-(3-butenyl)cyclohexyl)cyclohexyl-4-chlorobenzene;

1-[trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexyl-3-fluoro-4-chlorobenzene:

1-[trans-4-[2-(trans-4-(3-butenyl)cyclohexyl)ethyl]-cyclohexyl]-3,4-difluorobenzene;

1-[trans-4-[2-(trans-4-(3-butenyl)cyclohexyl)ethyl]-cyclohexyl]-3-chloro-4-fluorobenzene;

1-[trans-4-[2-(trans-4-(3-butenyl)cyclohexyl)ethyl]-cyclohexyl]-4-chlorobenzene;

1-[trans-4-[2-(trans-4-(3-butenyl)cyclohexyl)ethyl]-cyclohexyl]-3-fluoro-4-chlorobenzene;

1-[[trans-4-(trans-4-(3-butenyl)cyclohexyl)cyclohexyl]-methoxy]-4-fluorobenzene,m.p. (C-N) 82.2° C., cl. p. (N-I) 131.7° C.;

1-[[trans-4-(trans-4-(3-butenyl)cyclohexyl)cyclohexyl]-methoxy]-3,4-difluorobenzene;

1-[[trans-4-(trans-4-(3-butenyl)cyclohexyl)cyclohexyl]-methoxy]-3-chloro-4-fluorobenzene;

1-[[trans-4-(trans-4-(3-butenyl)cyclohexyl)cyclohexyl]-methoxy]-4-chlorobenzene;

1-[[trans-4-(trans-4-(3-butenyl)cyclohexyl)cyclohexyl]-methoxy)-3-fluoro-4-chlorobenzene;

1-[2-[trans-4-(trans-4-(3-butenyl)cyclohexyl)cyclohexyl]ethyl]-3,4-difluorobenzene;

1-[2-(trans-4-(trans-4-(3-butenyl)cyclohexyl)cyclohexyl]ethyl]-3-chloro-4-fluorobenzene;

1-[2-[trans-4-(trans-4-(3-butenyl)cyclohexyl)cyclohexyl]ethyl]-4-chlorobenzene;

1-[2-(trans-4-(trans-4-(3-butenyl)cyclohexyl)cyclohexyl]ethyl]-3-fluoro-4-chlorobenzene;

3,4-difluorobenzoic acidtrans-4-[trans-4-(3-butenyl)-cyclohexyl]cyclohexyl ester;

3-chloro-4-fluorobenzoic acidtrans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexyl ester;

4-chlorobenzoic acid trans-4-[trans-4-(3-butenyl)-cyclohexyl]cyclohexylester;

3-fluoro-4-chlorobenzoic acidtrans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexyl ester;

trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexyl 4-fluorobenzyl etherm.p. (C-N) 37.7° C., cl.p. (N-I) 92.8° C.;

trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexyl 3,4-difluorobenzylether;

trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexyl3-chloro-4-fluorobenzyl ether:

trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexyl 4-chlorobenzyl ether;

trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexyl3-fluoro-4-chlorobenzyl ether;

1-[trans-4-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexyl]-3,4-difluorobenzene;

1-[trans-4-[2-(trans-4-(3E-pentenyl)cyclohexyl)ethyl]-cyclohexyl]-3,4-difluorobenzene;

1-[[trans-4-(trans-4-(3E-pentenyl)cyclohexyl)cyclohexyl]methoxy]-4-fluorobenzene;

1-[[trans-4-(trans-4-(3E-pentenyl)cyclohexyl)cyclohexyl]methoxy]-3,4-difluorobenzene;

1-[2-[trans-4-(trans-4-(3E-pentenyl)cyclohexyl)cyclohexyl]ethyl]-3,4-difluorobenzene;

trans-4-[trans-4-(3E-pentenyl)cyclohexyl)cyclohexyl 4-fluorobenzylether;

trans-4-(trans-4-(3E-pentenyl)cyclohexyl]cyclohexyl 3,4-difluorobenzylether;

3,4-difluorobenzoic acidtrans-4-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexyl ester;

trans-4-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexyl 3,4-difluorobenzylether.

EXAMPLE 10

a) A suspension of 1.20 g of lithium aluminium hydride in 50 ml ofdiethyl ether was treated dropwise within 15 minutes with a solution of6.67 g of trans-4-(4-fluorophenyl)cyclohexanecarboxylic acid in 200 mlof diethyl ether and 40 ml of tetrahydrofuran. The reaction mixture wasstirred at room temperature for 2 hours, then treated dropwise with 4 mlof acetone and 14 ml of water and made acid (pH about 1) with 3Nhydrochloric acid. The aqueous phase was separated. The organic phasewas washed with 30 ml of water, twice with 20 ml of semi-saturatedsodium carbonate solution each time and three times with 30 ml of watereach time, dried over sodium sulfate and evaporated. There were thusobtained 6.08 g of crude [trans-4-(4-fluorophenyl)cyclohexyl]methanolwith m.p. 65°-70° C.

b) A suspension of 11.35 g of pyridinium chlorochromate in 80 ml ofdichloromethane was treated dropwise with a solution of 6.06 g of(trans-4-(4-fluorophenyl)cyclohexyl]methanol in 18 ml of diethyl ether.The reaction mixture was stirred for 4 hours, then diluted with 50 ml ofdiethyl ether, decanted off from the dark residue and filtered.Concentration of the filtrate gave 4.86 g oftrans-4-(4-fluorophenyl)cyclohexanecarboxaldehyde as a yellowish oilwhich solidified at room temperature; m.p. <30° C.

EXAMPLE 11

A solution of 0.98 g of 2-(4-pentenyl)-1,3-propanediol and 1.34 g oftrans-4-(4-fluorophenyl)cyclohexanecarboxaldehyde in 40 ml of toluenewas treated with 4 drops of 10 percent sulfuric acid in a sulfonationflask equipped with a descending condenser. The mixture was boiled for 1hour, with the damp solvent which was distilled off being replaced bythe dropwise addition of fresh toluene. Subsequently, the reactionmixture was neutralized with triethylamine (about 8 drops), washed twicewith 15 ml of water each time, dried over sodium sulfate, filtered andconcentrated. Chromatographic purification of the residue (2.22 g) onsilica gel with hexane/ethyl acetate (vol. 39:1) and repeatedrecrystallization from ethanol finally gave 0.44 g of puretrans-2-[trans-4-(4-fluorophenyl)cyclohexyl]-5-(4-pentenyl)-m-dioxane;m.p. (C-S_(B)) 68.5° C., phase transition (S_(B) -N) 77° C., cl.p. (N-1)96.5° C.

The following compounds can be prepared in an analogous manner:

trans-2-[trans-4-(3,4-difluorophenyl)cyclohexyl]-5-(4-pentenyl)-m-dioxane;

trans-2-[trans-4-(4-chlorophenyl)cyclohexyl]-5-(4-pentenyl)-m-dioxane;

trans-2-[trans-4-(3,4-difluorophenyl)cyclohexyl]-5-(3-butenyl)-m-dioxane;

trans-2-(trans-4-(4-chlorophenyl)cyclohexyl]-5-(3-butenyl)-m-dioxane:

trans-2-[trans-4-[2-(4-fluorophenyl)ethyl]cyclohexyl]-5-(4-pentenyl)-m-dioxane;

trans-2-[trans-4-[2-(3,4-difluorophenyl)ethyl]cyclohexyl]-5-(4-pentenyl)-m-dioxane;

trans-2-[trans-4-[2-(4-chlorophenyl)ethyl]cyclohexyl]-5-(4-pentenyl)-m-dioxane;

trans-2-[trans-4-[2-(3,4-difluorophenyl)ethyl]cyclohexyl]-5-(3-butenyl)-m-dioxane;

trans-2-[trans-4-[2-(4-chlorophenyl)ethyl]cyclohexyl]-5-(3-butenyl)-m-dioxane;

trans-2-(4-fluorophenyl)-5-(4-pentenyl)-m-dioxane, m.p. (C-I) 18.7° C.;

trans-2-(3,4-difluorophenyl)-5-(4-pentenyl)-m-dioxane;

trans-2-(4-chlorophenyl)-5-(4-pentenyl)-m-dioxane;

trans-2-(3,4-difluorophenyl)-5-(3-butenyl)-m-dioxane;

trans-2-(4-chlorophenyl)-5-(3-butenyl)-m-dioxane;

trans-2-[2-(4-fluorophenyl)ethyl]-5-(4-pentenyl)-m-dioxane;

trans-2-[2-(3,4-difluorophenyl)ethyl]-5-(4-pentenyl)-m-dioxane;

trans-2-[2-(4-chlorophenyl)ethyl]-5-(4-pentenyl)-m-dioxane;

trans-2-[2-(3,4-difluorophenyl)ethyl]-5-(3-butenyl)-m-dioxane;

trans-2-[2-(4-chlorophenyl)ethyl]-5-(3-butenyl)-m-dioxane.

EXAMPLE 12

A mixture of 3.6 g of 7-dimethoxy-6-(dimethoxymethyl)-1-heptene, 75 mgof p-toluenesulfonic acid monohydrate and 0.35 ml of water was heated toslight boiling for 2 hours in an oil bath of 110° C. while stirring andunder a nitrogen atmosphere. Thereafter, the mixture was treated with0.5 g of sodium hydrogen carbonate, stirred for 10 minutes without theoil bath and then filtered (rinsing with a small amount of methanol).The filtrate was added to a solution of 2.9 g of 4-fluorobenzamidinehydrochloride in 60 ml of methanol. Subsequently, the reaction mixturewas treated dropwise with a sodium methylate solution (prepared from 0.6g of sodium and 15 ml of methanol), stirred at room temperatureovernight, then adjusted to pH 5 with concentrated hydrochloric acid andevaporated. The residue was treated with water and extracted withdiethyl ether. The organic phase was washed with water, dried oversodium sulfate, filtered and evaporated. Chromatographic purification ofthe crude product on silica gel with hexane/ethyl acetate (vol. 19:1)and recrystallization from hexane gave 1.0 g of pure2-(4-fluorophenyl)-5-(4-pentenyl)pyrimidine with m.p. 21.8° C.

The following compounds can be prepared in an analogous manner:

2-(3,4-Difluorophenyl)-5-(4-pentenyl)pyrimidine;

2-(4-chlorophenyl)-5-(4-pentenyl)pyrimidine;

2-(3,4-difluorophenyl)-5-(3-butenyl)pyrimidine;

2-(4-chlorophenyl)-5-(3-butenyl)pyrimidine;

2-(4-fluorophenyl)-5-[trans-4-(4-pentenyl)cyclohexyl]-pyrimidine;

2-(3,4-difluorophenyl)-5-[trans-4-(4-pentenyl)cyclohexyl]pyrimidine;

2-(4-chlorophenyl)-5-[trans-4-(4-pentenyl)cyclohexyl]-pyrimidine;

2-(3,4-difluorophenyl)-5-[trans-4-(3-butenyl)cyclohexyl]pyrimidine;

2-(4-chlorophenyl)-5-[trans-4-(3-butenyl)cyclohexyl]-pyrimidine;

2-(4'-fluoro-4-biphenylyl)-5-(4-pentenyl)pyrimidine;

2-(3',4'-difluoro-4-biphenylyl)-5-(4-pentenyl)-pyrimidine;

2-(4'-chloro-4-biphenylyl)-5-(4-pentenyl)pyrimidine;

2-(3',4'-difluoro-4-biphenylyl)-5-(3-butenyl)pyrimidine;

2-(3'-chloro-4-biphenylyl)-5-(3-butenyl)pyrimidine.

EXAMPLE 13

The binary mixtures set forth hereinafter were prepared from4-(trans-4-pentenylcyclohexyl)benzonitrile and a compound of formula I.The electro-optical data were measured at 22° C. in a TN cell having aplate separation of 8 μm. The corresponding values for4-(trans-4-pentylcyclohexyl)benzonitrile are: V₁₀ =1.62V, t_(on) =30 ms,Δn=0.120; cl.p. (N-I) 54.6° C.

Mixture 1

90 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile,

10 wt.% of 4-(3-butenyloxy)benzoic acid 4-fluorophenyl ester;

V₁₀ =1.29V, t_(on) =31 ms, Δn=0.117.

Mixture 2

90 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile,

10 wt.% of trans-4-(4-pentenyl)cyclohexanecarboxylic acid 4-fluorophenylester;

V₁₀ =1.17V, t_(on) =22 ms, Δn=0.108.

Mixture 3

70 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile,

30 wt.% of trans-4-(trans-4-(4-pentenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester;

V₁₀ =1.55V, t_(on) =44 ms, Δn=0.110;

cl.p. (N-I) 75.3° C.

Mixture 4

90 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile,

10 wt.% of 4-(4-pentenyl)benzoic acid 4-fluorophenyl ester;

V₁₀ =1.42V, t_(on) =26 ms, Δn=0.117,

cl.p. (N-I) 50.3° C.

Mixture 5

90 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile,

10 wt.% of 4-(3-butenyloxy)benzoic acid 3,4-difluorophenyl ester;

V₁₀ =1.23V, t_(on) =36 ms, Δn=0.116,

cl.p. (N-I) 44.5° C.

Mixture 6

90 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile,

10 wt.% of1-(trans-4-(trans-4-(4-pentenyl)cyclohexyl]cyclohexyl]-4-fluorobenzene;

V₁₀ =1.47V, t_(on) =25 ms, Δn=0.112,

cl.p. (N-I) 59.1° C.

Mixture 7

90 wt.% of 4-(trans-4-pentylcyclohexyl)benzonitrile,

10 wt.% oftrans-2-[trans-4-(4-fluorophenyl)cyclohexyl]-5-(4-pentenyl)-m-dioxane:

V₁₀ =1.34V, t_(on) =31 ms, Δn=0.116.

cl.p. (N-I) 54.0° C.

EXAMPLE 14

The following mixtures were prepared. Unless stated otherwise, theelectro-optical data were measured at 22° C. in a TN cell having a plateseparation of 6 μm.

Mixture A

15 wt.% oftrans-4-(trans-4-(3-butenyl)cyclohexyl]cyclohexanecarbonitrile,

12 wt.% oftrans-4-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexanecarbonitrile,

10 wt.% oftrans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexanecarbonitrile,

10 wt.% of 4-[trans-4-(1E-propenyl)cyclohexyl]benzonitrile,

20 wt.% of trans-4-allyloxy-1-(trans-4-propylcyclohexyl)-cyclohexane,

15 wt.% of 4-ethoxy-1-[trans-4-(3E-pentenyl)cyclohexyl]-benzene,

10 wt.% of trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester,

8 wt.% of trans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester;

m.p.<-30° C., cl.p. (N-I) 71° C.; V₁₀ =2.10V, p=0.204, t_(on) =19 ms,t_(off) =31 ms, Δn=0.084.

Mixture B

15 wt.% oftrans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarbonitrile,

12 wt.% oftrans-4-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexanecarbonitrile,

10 wt.% oftrans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexanecarbonitrile,

33 wt.% of trans-4-allyloxy-1-(trans-4-propylcyclohexyl)-cyclohexane,

20 wt.% of trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester,

10 wt.% of trans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester;

m.p.<-20° C., cl.p. (N-I) 81° C.; V₁₀ =2.41V, p=0.211, t_(on) =24 ms,t_(off) 37 ms, Δn=0.067.

Mixture C

10 wt.% of 4-[trans-4-(1E-propenyl)cyclohexyl]benzonitrile,

15 wt.% of 4-ethoxy-1-[trans-4-(3E-pentenyl)cyclohexyl]-benzene,

12 wt.% oftrans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarbonitrile,

10 wt.% oftrans-4-[trans-4-(3E-pentenyl)cyclohexyllcyclohexanecarbonitrile,

8 wt.% oftrans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexanecarbonitrile,

15 wt.% of trans-4-(3-butenyl)-1-(trans-4-ethoxycyclohexyl)-cyclohexane,

8 wt.% of1-[2-(trans-4-butylcyclohexyl)ethyl]-4-(trans-4-pentylcyclohexyl)benzene,

8 wt.% of trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester,

8 wt.% of trans-4-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester,

6 wt.% of trans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester;

m.p.<-30° C. cl.p. 84° C. nematic; V₁₀ =2.35V; t_(on) (22° C.)=15 ms,t_(on) (-20° C.)=309 ms, t_(off) (22° C.)=27 ms, t_(off) (-20° C.)=420ms; Δn=0.088.

Mixture D

10 wt.% of 4-[trans-4-(1E-propenyl)cyclohexyl]benzonitrile,

6 wt.% of 4-[trans-4-(3E-propenyl)cyclohexyl]benzonitrile,

12 wt.% of 4-ethoxy-1-[trans-4-(3E-pentenyl)cyclohexyl]-benzene,

5 wt.% oftrans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarbonitrile,

7 wt.% oftrans-4-[trans-4-(3E-pentenyl)cyclohexyl)cyclohexanecarbonitrile,

12 wt.% of trans-4-allyloxy-1-(trans-4-propylcyclohexyl)-cyclohexane,

10 wt.% oftrans-4-(3E-pentenyl)-1-(trans-4-ethoxycyclohexyl)cyclohexane,

6 wt.% of 4-[trans-4-(3E-pentenyl)cyclohexyll-4'-propylbiphenyl,

6 wt.% of trans-4-propylcyclohexanecarboxylic acid4-(trans-4-(3E-pentenyl)cyclohexyl]phenyl ester,

10 wt.% of1-[2-(trans-4-butylcyclohexyl)ethyl]-4-(trans-4-pentylcyclohexyl)benzene,

4 wt.% of4-[2-(trans-4-butylcyclohexyl)ethyl)-4'-(trans-4-(3E-pentenyl)cyclohexyl]biphenyl,

8 wt.% of trans-4-(trans-4-(3-butenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester,

4 wt.% of trans-4-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester;

m.p.<-30° C., cl.p. 100° C. nematic; V₁₀ =2.82V, t_(on) (22° C.)=12 ms,t_(on) =(-20° C.)=220 ms, t_(off) (22° C.)=21 ms, t_(off) (-20° C.)=330ms; Δn=0.105.

Mixture E

9.40 wt.% of 4-[trans-4-(1E-propenyl)cyclohexyl]benzonitrile,

5.64 wt.% of 4-[trans-4-(3E-pentenyl)cyclohexyl]benzonitrile,

11.28 wt.% of 4-ethoxy-1-[trans-4-(3E-pentenyl)cyclohexyl]-benzene,

4.70 wt.% oftrans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarbonitrile,

6.58 wt.% oftrans-4-[trans-4-(3E-pentenyl)cyclohexyl]-cyclohexanecarbonitrile,

11.28 wt.% of trans-4-allyloxy-1-(trans-4-propylcyclohexyl)-cyclohexane.

9.40 wt.% oftrans-4-(3E-pentenyl)-1-(trans-4-ethoxycyclohexyl)cyclohexane,

6.00 wt.% of 2-cyano-5-(trans-4-butylcyclohexyl)-pyrimidine,

5.64 wt.% of trans-4-propylcyclohexanecarboxylic acid4-[trans-4-(3E-pentenyl)cyclohexyl]phenyl ester,

5.64 wt.% of 4-[trans-4-(3-pentenyl)cyclohexyl]-4'-propylbiphenyl,

9.40 wt.% of1-[2-(trans-4-butylcyclohexyl)ethyl]-4-(trans-4-pentylcyclohexyl)benzene,

3.76 wt.% of4-[2-(trans-4-butylcyclohexyl)ethyl)-4'-[trans-4-(3E-pentenyl)cyclohexyl]biphenyl,

7.52 wt.% oftrans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarboxylic acid4-fluorophenyl ester,

3.76 wt.% oftrans-4-(trans-4-(3E-pentenyl)cyclohexyl]cyclohexanecarboxylic acid4-fluorophenyl ester;

m.p.<-30° C., cl.p. 95° C., nematic; V₁₀ =2.35V, t_(on) (22° C.)=16 ms,t_(on) =(-20° C.)=300 ms, t_(off) (22° C.)=24 ms, t_(off) (-20° C.)=350ms; Δn=0.104.

Mixture F

10 wt.% of 4-(trans-4-(1E-propenyl)cyclohexyl]benzonitrile,

12 wt.% of 4-(2E-butenyloxy)-1-(trans-4-propylcyclohexyl)-benzene,

5 wt.% oftrans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarbonitrile,

7 wt.% oftrans-4-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexanecarbonitrile,

6 wt.% oftrans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexanecarbonitrile,

12 wt.% of trans-4-allyloxy-1-(trans-4-propylcyclohexyl)cyclohexane,

10 wt.% oftrans-4-(3E-pentenyl)-1-(trans-4-ethoxycyclohexyl)cyclohexane,

8 wt.% of trans-4-propylcyclohexanecarboxylic acid4-[trans-4-(3E-pentenyl)cyclohexyl]phenyl ester,

10 wt.% of1-[2-(trans-4-butylcyclohexyl)ethyl]-4-(trans-4-pentylcyclohexyl)benzene,

5 wt.% of4-[2-(trans-4-butylcyclohexyl)ethyl]-4-(trans-4-pentylcyclohexyl)biphenyl,

3 wt.% of5-(trans-4-pentylcyclohexyl)-2-[4-(trans-4-propylcyclohexyl)phenyl]pyrimidine,

4 wt.% of trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester,

8 wt.% of trans-4-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester;

m.p.<-30° C. cl.p. 109° C. nematic; V₁₀ =2.84V, t_(on) (22° C.)=16 ms,t_(on) =(-20° C.)=336 ms, t_(off) (22° C.)=26 ms, t_(off) (<20° C.)=370ms; Δn=0.096.

Mixture G

10 wt.% of 4-(trans-4-propylcyclohexyl)benzonitrile,

8 wt.% of 4-(trans-4-(1E-propenyl)cyclohexyl]benzonitrile,

10 wt.% of trans-4-(trans-4-vinylcyclohexyl)cyclohexanecarbonitrile,

8 wt.% oftrans-4-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexanecarbonitrile,

wt.% of trans-4-ethoxy-1-(trans-4-(3E-pentenyl)cyclohexyl]cyclohexane,

8 wt.% of trans-4-ethoxy-1-(trans-4-(4-pentenyl)cyclohexyl]cyclohexane,

8 wt.% of 2-cyano-5-(trans-4-butylcyclohexyl)pyritnidine,

3 wt.% of 2-cyano-5-(trans-4-pentylcyclohexyl)pyrimidine,

7 wt.% of4-(2E-butenyloxy)-1-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]benzene,

5 wt.% oftrans-4-[5-(trans-4-butylcyclohexyl)-2-pyrimidinyl]cyclohexanecarbonitrile

8 wt.% of trans-4-propylcyclohexanecarboxylic acid4-[trans-4-(3E-pentenyl)cyclohexyl]phenyl ester,

7 wt.% of1-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]-4-fluorobenzene,

5 wt.% of trans-4-[trans-4-(3-butenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester,

7 wt.% of trans-4-[trans-4-(4-pentenyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester;

m.p.<-30° C. cl.p. 92° C., nematic; V₁₀ =1.71V, t_(on) (22° C.)=19 ms,t_(on) (-20° C.)=530 ms, t_(off) (22° C.)=34 ms, t_(off) (-20° C.)=772ms, Δn=0.094.

Mixture H

7 wt.% of 4-(trans-4-propylcyclohexyl)benzonitrile.

8 wt.% of 4-(trans-4-(1E-propenyl)cyclohexyl)benzonitrile,

10 wt.% of trans-4-(trans-4-vinylcyclohexyl)cyclohexanecarbonitrile,

10 wt.% oftrans-4-methoxy-1-(trans-4-(3E-pentenyl)cyclohexyl]cyclohexane,

10 wt.% of trans-4-ethoxy-1-[trans-4-(3-butenyl)cyclohexyl]-cyclohexane,

12 wt.% oftrans-4-ethoxy-1-[trans-4-(3E-pentenyl)cyclohexyl)cyclohexane,

8 wt.% of1-[2-(trans-4-butylcyclohexyl)ethyl]-4-(trans-4-pentylcyclohexyl)benzene,

6 wt.% of trans-4-propylcyclohexanecarboxylic acid4-[trans-4-(3E-pentenyl)cyclohexyl]phenyl ester,

8 wt.% of1-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]-4-fluorobenzene,

6 wt.% of1-[trans-4-(trans-4-vinylcyclohexyl)cyclohexyl]-4-fluorobenzene,

4 wt.% of4-[2-(trans-4-butylcyclohexyl)ethyl]-4'-[trans-4-(3E-pentenyl)cyclohexyl]biphenyl,

3 wt.% of5-(trans-4-pentylcyclohexyl)-2-[4-(trans-4-propylcyclohexyl)phenyl]pyrimidine,

8 wt.% of trans-4-(4-pentenyl)cyclohexanecarboxylic acid 4-fluorophenylester;

m.p.<-30° C., cl.p. 88° C., nematic; V₁₀ 2.29V, t_(on) (22° C.)=12 ms,t_(on) (-20° C.)=221 ms, t_(off) (22° C.)=23 ms, t_(off) (-20° C.)=296ms, Δn=0.080.

Mixture I

7 wt.% of 4-(trans-4-propylcyclohexyl)benzonitrile,

8 wt.% of 4-(trans-4-(1E-propenyl)cyclohexyl)benzonitrile,

10 wt.% of trans-4-(trans-4-vinylcyclohexyl)cyclohexanecarbonitrile,

10 wt.% oftrans-4-methoxy-1-(trans-4-(3E-pentenyl)cyclohexyl]cyclohexane,

10 wt.% of trans-4-ethoxy-1-[trans-4-(3-butenyl)cyclohexyl]-cyclohexane,

12 wt.% oftrans-4-ethoxy-1-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexane,

8 wt.% of1-[2-(trans-4-butylcyclohexyl)ethyl]-4-(trans-4-pentylcyclohexyl)benzene,

6 wt.% of trans-4-propylcyclohexanecarboxylic acid4-[trans-4-(3E-pentenyl)cyclohexyl]phenyl ester,

8 wt.% of1-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]-4-fluorobenzene,

6 wt.% of1-[trans-4-(trans-4-vinylcyclohexyl)cyclohexyl]-4-fluorobenzene,

4wt.% of4-(2-(trans-4-butylcyclohexyl)ethyl]-4'-[trans-4-(3E-pentenyl)cyclohexyl]biphenyl,

3 wt.% of5-(trans-4-pentylcyclohexyl)-2-[4-(trans-4-propylcyclohexyl)phenyl]pyrimidine,

8 wt.% of trans-2-(4-fluorophenyl)-5-(4-pentenyl)-m-dioxane;

m.p.<-30° C. cl.p. 81° C. nematic; V₁₀ =2.15V, t_(on) (22° C.)=14 ms,t_(on) (-20° C.)=249 ms, t_(off) (22° C.)=26 ms, t_(off) (-20° C.)=342ms, Δn=0.087.

Mixture J

10 wt.% of 4-(trans-4-propylcyclohexyl)benzonitrile,

7 wt.% of 4-(trans-4-vinylcyclohexyl)benzonitrile,

8 wt.% of 4-[trans-4-(1E-propenyl)cyclohexyl]benzonitrile,

6 wt.% of 4-ethoxy-1-(trans-4-propylcyclohexyl)benzene,

10 wt.% oftrans-4-methoxy-1-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexane,

10 wt.% of trans-4-ethoxy-1-[trans-4-(3-butenyl)cyclohexyl]-cyclohexane,

12 wt.% oftrans-4-ethoxy-1-[trans-4-(3E-pentenyl)cyclohexyl]cyclohexane,

8 wt.% of4-(2E-butenyloxy)-1-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]benzene,

8 wt.% of1-[2-(trans-4-butylcyclohexyl)ethyl]-4-(trans-4-pentylcyclohexyl)benzene,

6 wt.% of trans-4-propylcyclohexanecarboxylic acid4-[trans-4-(3E-pentenyl)cyclohexyl]phenyl ester,

4 wt.% of 4,4'-bis-(trans-4-propylcyclohexyl)biphenyl,

3 wt.% of5-(trans-4-pentylcyclohexyl)-2-[4-(trans-4-propylcyclohexyl)phenyl]pyrimidine,

8 wt.% of trans-4-[trans-4-(4-pententyl)cyclohexyl]cyclohexanecarboxylicacid 4-fluorophenyl ester;

m.p.<-30° C., cl.p. 95° C. nematic; V₁₀ =2.41V, t_(on) (22° C.)=12 ms,t_(on) (-20° C.)=195 ms, t_(off) (22° C.)=21 ms. t_(off) (-20° C.)=276ms, Δn0.101.

We claim:
 1. A compound of the formula: ##STR7## wherein X¹ is chlorineand X² is hydrogen; R¹ is 3E-alkenyl, 4-alkenyl, 2E-alkenyloxy, or3-alkenyloxy; n is the integer 0 or 1; one of the groups Y¹ and Y² is asingle covalent bond, --COO--, --OOC--, --CH₂ CH₂ --, --CH₂ O--, or--OCH₂ -- and the other of the groups Y¹ and Y² is single covalent bond;and each of the rings A¹ and A² individually is trans-1,4-cyclohexylene,trans-1,4-cyclohexylene in which in two non-adjacent CH₂ groups arereplaced by oxygen, 1,4-phenylene, or 1,4-phenylene in which 1 CH groupor 2 CH groups are replaced by nitrogen, the above substituents forrings A¹ and A² being unsubstituted or substituted with at least one ofcyano, lower alkyl, or halo.
 2. The compound of claim 1, wherein ring A¹is substituted or unsubstituted trans-1,4-cyclohexylene, substituted orunsubstituted 1,4-phenylene or pyridine-2,5-diyl, pyrimidine-2,5-diyl orpyrazine-2,5-diyl.
 3. The compound of claim 1, wherein ring A² issubstituted or unsubstituted trans-1,4-cyclohexylene, substituted orunsubstituted 1,4-phenylene or, when ring A¹ is substituted orunsubstituted trans-1,4-cyclohexylene or substituted or unsubstituted1,4-phenylene, ring A² also can be pyrimidine-2,5-diyl ortrans-m-dioxane-2,5-diyl.
 4. The compound of claim 1, wherein ring A¹ istrans-1,4-cyclohexylene, 1,4-phenylene, pyridine-2,5-diyl,pyrimidine-2,5-diyl or pyrazine-2,5-diyl and ring A² istrans-1,4-cyclohexylene.
 5. The compound of claim 1, having the formula##STR8## wherein R¹, X¹, X² and Y¹ have the significances given inclaim
 1. 6. The compound of claim 1, wherein R¹ is a straight-chainresidue having the significance given in claim
 1. 7. The compound ofclaim 1, wherein R¹ is 3E-alkenyl with 4 to 15 carbon atoms, 4-alkenylwith 5 to 15 carbon atoms, 2E-alkenyloxy with 3 to 14 carbon atoms or3-alkenyloxy with 4 to 14 carbon atoms.
 8. A liquid crystalline mixturehaving at least two components, wherein at least one of such componentsis a compound of the formula: ##STR9## wherein X¹ is chlorine and X² ishydrogen; R¹ is 3-E-alkenyl, 4-alkenyl, 2E-alkenyloxy, or 3-alkenyloxy;n is the integer 0 or 1; one of the groups Y¹ and Y² is a singlecovalent bond, --COO--, --OOC--, --CH₂ CH₂ --, --CH₂ O--, or --OCH₂ --and the other of the groups Y¹ and Y² is single covalent bond; and eachof the rings A¹ and A² individually is trans-1,4-cyclohexylene,trans-1,4-cyclohexylene in which in two non-adjacent CH₂ groups arereplaced by oxygen, 1,4-phenylene, or 1,4-phenylene in which 1 CH groupor 2 CH groups are replaced by nitrogen, the above substituents forrings A¹ and A² being unsubstituted or substituted with at least one ofcyano, lower alkyl, or halo.
 9. An electro-optical cell comprising:(a)two plate means; (b) liquid crystal means disposed between two platemeans including a compound of the formula: ##STR10## wherein X¹ ischlorine and X² is hydrogen; R¹ is 3E-alkenyl, 4-alkenyl, 2E-alkenyloxy,or 3-alkenyloxy; n is the integer 0 or 1; one of the groups Y¹ and Y² isa single covalent bond, --COO--, --OOC--, --CH₂ CH₂ --, --CH₂ O--, or--OCH₂ -- and the other of the groups Y¹ and Y² is single covalent bond;and each of the rings A¹ and A² individually is trans-1,4-cyclohexylene,trans-1,4-cyclohexylene in which in two non-adjacent CH₂ groups arereplaced by oxygen, 1,4-phenylene, or 1,4-phenylene in which 1 CH groupor 2 CH groups are replaced by nitrogen, the above substituents forrings A¹ and A² being unsubstituted or substituted with at least one ofcyano, lower alkyl, or halo; and (c) means for applying an electricalpotential to said plate means.